免疫疗法治疗小鼠纤维化

StephenW

免疫疗法治疗小鼠纤维化
研究人员报告说，针对促纤维化细胞上发现的蛋白质接种疫苗可减少实验室啮齿动物的肝和肺纤维化。
亚历杭德拉·曼贾雷斯

2022 年 9 月 15 日

由于各种原因而面临慢性损伤或炎症的器官可能容易受到长期修复过程的影响，最终会在组织中产生永久性疤痕，称为纤维化，这可能导致器官功能障碍甚至死亡。一项估计表明，器官纤维化可能导致美国 45% 的死亡。纤维化的治疗选择稀缺且有许多局限性，而且在不影响健康细胞的情况下，针对纤维化细胞的治疗选择更少。
参见“CAR T 细胞修复破碎的老鼠心脏”

今天（9 月 15 日）在 Cell Stem Cell 上发表的一项研究证明了一种潜在的新疗法的原理，该疗法基于针对仅存在于产生肌成纤维细胞的细胞中的肽的疫苗接种——这些细胞负责永久性瘢痕组织。作者报告说，与接受对照注射的小鼠相比，接受这些疫苗的小鼠肝脏和肺部的纤维化水平降低。

在过去的十年中，各种研究发现某些基因在与器官纤维化相关的细胞中短暂表达——以前认为这些基因只在胚胎发生过程中活跃。使用追踪工具，这些“优雅的论文”表明，表达这些基因的细胞“基本上会产生导致纤维化问题的所有成纤维细胞，”苏黎世大学解剖学研究所的免疫学家、新论文的合著者克里斯蒂安斯托克曼说。纸。 Stockmann 和他的同事想知道这些蛋白质是否可以作为免疫细胞（如 T 细胞）识别促纤维化细胞的标签。

研究人员推断，这些独特蛋白质的片段会被主要组织相容性复合物 (MHC) I 类分子降解，这些分子位于大多数细胞的表面，并向 T 细胞展示细胞内蛋白质的片段。当外源肽出现在所呈现的片段中时，会触发免疫反应，T 细胞会杀死受感染的细胞。因此，科学家们认为可能有一种方法可以让免疫系统以类似的方式对含有促纤维化蛋白的细胞做出反应。

该团队关注的识别蛋白质之一是 ADAM12，它属于一个能够抵消血液凝固步骤的蛋白质家族（尽管它的功能对于预期的方法无关紧要）。 Stockmann 和他的同事在计算机、体外和体内进行了一系列测试，以评估 ADAM12 是否可能成为激活 T 细胞的潜在候选者。当分析和实验表明确实如此时，该团队构建了一种针对它的疫苗，其中包含一个慢病毒外壳，其中包含编码 Adam12 的 DNA 序列以及用于刺激免疫系统的佐剂，小鼠将接受该免疫系统作为初始免疫，并且在 7 天后，作为助推器。

该团队测试了在小鼠体内诱导肝纤维化之前或之后接种疫苗的效果。在这两种情况下，与接受对照疫苗的小鼠相比，在治疗 6 周后，小鼠的纤维化水平（基于分子和细胞标志物）均有所降低。 Stockmann 和他的同事使用 ADAM12 疫苗或靶向转录因子 GLI1 的第二种疫苗在肺纤维化小鼠中重复了相同的过程，该转录因子 GLI1 也对促纤维化细胞具有特异性。两种注射都减少了治疗小鼠的肺纤维化，其水平与接种疫苗的肝纤维化小鼠记录的水平相似。研究人员还证明，这些抗纤维化作用是由 CD8+ T 细胞介导的：当这些细胞群在小鼠体内被故意耗尽时，疫苗的作用就完全消失了。

“我认为他们在使用多种不同的纤维化模型（肝脏和肺部）以及两个不同的靶点方面做得很好，”圣路易斯华盛顿大学医学院的肾病学家 Benjamin Humphreys 说。参与了这项研究，并描述了 Gli1 在纤维化中的表达。此外，这种治疗在纤维化开始之前和之后都有效，他补充道，“这真的很关键，因为如果你设想用这种方法治疗人类。 . .疫苗接种策略，总是在疾病开始之后。”
最后，斯托克曼和他的同事在老鼠身上进行了一系列安全测试，以评估这种策略的潜在风险，因为它针对的是在身体其他部位低水平表达的基因。根据组织学变化和血液标志物，他们在免疫后 4 周发现接种疫苗的小鼠的主要器官没有明显损伤。这些动物在愈合反应方面也没有表现出任何问题的迹象。

未参与该研究的澳大利亚圣母大学免疫学家 Gerard Hoyne 表示，这些测试“非常重要”，因为疫苗针对的是个体自身的蛋白质，并可能影响身体的其他正常过程。他说，“他们没有看到任何证据表明这是一个积极的结果。”尽管如此，霍因指出，如果免疫系统对导致攻击健康细胞的疫苗产生挥之不去的反应，那么这在很长一段时间内都不会变得明显，研究人员只关注短期效应。 “至少在早期阶段，在对该疫苗的急性反应中，它似乎并没有推动一般的自身免疫反应，这很好，”他说，但补充说，“这并不排除可能成为动物生命后期的影响，我们还不了解。”

Humphreys 是 Pfizer、Janssen 和 Chinook Therapeutics 的顾问并持有其研究资助，并拥有后者的股权，他同意需要进一步的临床前调查。研究人员需要“更好地了解这种治疗方法如何在多种纤维化模型、多种器官和. . .确保我们真正了解体内平衡对健康器官的影响，”他说，并得出结论，在尝试将其转化为人类之前，等待并更多地了解这种方法的后果很重要。
关键词：
药物开发 成纤维细胞 免疫学 免疫治疗 肝病 肺病 MHC 分子 小鼠模型 新闻 T细胞 疫苗 疫苗 疫苗设计

StephenW

Immunotherapy Treats Fibrosis in Mice
Researchers report that vaccination against proteins found on profibrotic cells reduced liver and lung fibrosis in laboratory rodents.
alejandra manjarrez

Sep 15, 2022

Organs facing chronic injury or inflammation from a variety of causes may be susceptible to a prolonged repair process that ultimately creates a permanent scarring of the tissue, known as fibrosis, which can lead to organ dysfunction and even death. One estimate suggests that organ fibrosis may contribute to 45 percent of deaths in the US. Treatment options for fibrosis are scarce and have many limitations, and fewer still target fibrotic cells without affecting healthy ones.
See “CAR T Cells Mend Broken Mouse Hearts”

A study published today (September 15) in Cell Stem Cell provides proof of principle of a potential new treatment based on vaccination against peptides that are only present in the cells that give rise to myofibroblasts—those responsible for the permanent scar tissue. Mice that received these vaccines showed reduced levels of fibrosis in their livers and lungs compared to those that received a control injection, the authors report.

In the past decade, various studies have found transient expression of certain genes—previously thought to be active only during embryogenesis—in cells associated with organ fibrosis. Using tracing tools, these “elegant papers” have shown that cells expressing these genes “basically give rise to all the fibroblasts that cause problems in fibrosis,” says Christian Stockmann, an immunologist at the University of Zurich’s Institute of Anatomy and coauthor of the new paper. Stockmann and his colleagues wondered whether these proteins could serve as tags for immune cells such as T cells to recognize profibrotic cells.

The researchers reasoned that fragments of these distinctive proteins would be degraded by major histocompatibility complex (MHC) class I molecules, which are located on the surfaces of most cells and display fragments of intracellular proteins to T cells. When a foreign peptide is among the presented fragments, an immune response is triggered and T cells kill the infected cells. So the scientists thought there might be a way to get the immune system to respond in a similar way to cells with the profibrotic proteins.

One of the identifying proteins the team focused on was ADAM12, which belongs to a family of proteins that counteract steps in blood clotting (although its function matters little for the intended approach). Stockmann and his colleagues conducted a series of tests in silico, in vitro, and in vivo to assess whether ADAM12 could be a potential candidate to activate T cells. When the analyses and experiments suggested it was, the team constructed a vaccine against it that contained a lentivirus shell housing a DNA sequence encoding Adam12 together with adjuvants to stimulate the immune system, which mice would receive as a prime immunization and, seven days later, as a booster.

The team tested the effects of the vaccine administered either before or after they induced liver fibrosis in mice. In both scenarios, mice showed reduced levels of fibrosis—based on molecular and cellular markers—after 6 weeks of treatment, compared with mice that received a control vaccine. Stockmann and his colleagues repeated the same process in mice with lung fibrosis using either the ADAM12 vaccine or a second vaccine targeting the transcription factor GLI1, which is also specific to profibrotic cells. Both injections lessened lung fibrosis in the treated mice at levels similar to those recorded in the vaccinated mice with liver fibrosis. The researchers also demonstrated that those antifibrotic effects were mediated by CD8+ T cells: When these cell populations were purposely depleted in the mice, the effect of the vaccines was completely abolished.

“I think they did a good job of using multiple different models of fibrosis—in the liver and in the lung—and two different targets,” says Benjamin Humphreys, a nephrologist at the Washington University School of Medicine in St. Louis who was not involved in the study and who has characterized the expression of Gli1 in fibrosis. Moreover, the treatment worked both before and after fibrosis began, he adds, and “that’s really critical because if you were to envision treating humans with this . . . vaccination strategy, it would always be after the disease has been initiated.”
Finally, Stockmann and his colleagues conducted a series of safety tests in mice to assess the potential risks of such a strategy, since it targets genes that are expressed at low levels in other parts of the body. Based on histological changes and blood markers, they found no evident damage to major organs in vaccinated mice four weeks after immunization. The animals showed no signs of problems in healing responses either.

These tests are “really important” since the vaccine targets the individual’s own proteins and could potentially affect other, normal processes in the body, says University of Notre Dame Australia immunologist Gerard Hoyne, who did not participate in the study. That “they didn’t see any evidence for that [is] a positive outcome,” he says. Nonetheless, Hoyne points out that if the immune system were to mount a lingering reaction to the vaccine that results in attacking healthy cells, that would not become evident for a long time, and the researchers looked only for short-term effects. “At least in the early stage, in the acute response to that vaccine, it doesn’t seem to be driving a general autoimmune response, which was good,” he says, but adds, “it doesn’t preclude that there maybe could be an effect later in the animal’s life which we don’t yet understand.”

Humphreys, who is a consultant for and has held research grants from Pfizer, Janssen, and Chinook Therapeutics, and owns equity in the latter, agrees that further preclinical investigation is needed. Researchers need “to better understand how does this therapeutic approach work across a diversity of fibrosis models, diversity of organs, and . . . make sure that we really understand effects in homeostasis, in healthy organs,” he says, concluding that it’s important to wait and learn more about the consequences of this approach before trying to translate it to humans.
Keywords:
drug development fibroblasts immunology immunotherapy liver liver disease lung lung disease MHC molecules mouse models News T cells vaccination vaccine vaccine design