Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, United States.
Department of Bioengineering, University of California San Diego, La Jolla, California 92093, United States.
Mol Pharm. 2023 Jul 3;20(7):3589-3597. doi: 10.1021/acs.molpharmaceut.3c00214. Epub 2023 Jun 9.
Plant virus nanoparticles can be used as drug carriers, imaging reagents, vaccine carriers, and immune adjuvants in the formulation of intratumoral in situ cancer vaccines. One example is the cowpea mosaic virus (CPMV), a nonenveloped virus with a bipartite positive-strand RNA genome with each RNA packaged separately into identical protein capsids. Based on differences in their densities, the components carrying RNA-1 (6 kb) denoted as the bottom (B) component or carrying RNA-2 (3.5 kb) denoted as the middle (M) component can be separated from each other and from a top (T) component, which is devoid of any RNA. Previous preclinical mouse studies and canine cancer trials used mixed populations of CPMV (containing B, M, and T components), so it is unclear whether the particle types differ in their efficacies. It is known that the CPMV RNA genome contributes to immunostimulation by activation of TLR7. To determine whether the two RNA genomes that have different sizes and unrelated sequences cause different immune stimulation, we compared the therapeutic efficacies of B and M components and unfractionated CPMV in vitro and in mouse cancer models. We found that separated B and M particles behaved similarly to the mixed CPMV, activating innate immune cells to induce the secretion of pro-inflammatory cytokines such as IFNα, IFNγ, IL-6, and IL-12, while inhibiting immunosuppressive cytokines such as TGF-β and IL-10. In murine models of melanoma and colon cancer, the mixed and separated CPMV particles all significantly reduced tumor growth and prolonged survival with no significant difference. This shows that the specific RNA genomes similarly stimulate the immune system even though B particles have 40% more RNA than M particles; each CPMV particle type can be used as an effective adjuvant against cancer with the same efficacy as native mixed CPMV. From a translational point of view, the use of either B or M component vs the mixed CPMV formulation offers the advantage that separated B or M alone is noninfectious toward plants and thus provides agronomic safety.
植物病毒纳米颗粒可用作药物载体、成像试剂、疫苗载体和免疫佐剂，用于构建肿瘤内原位癌症疫苗。例如，豇豆花叶病毒（CPMV）是一种无包膜的病毒，具有分段的正链 RNA 基因组，每个 RNA 分别包装在相同的蛋白衣壳中。根据其密度的差异，可以将携带 RNA-1（6kb）的成分（表示为底部（B）成分）或携带 RNA-2（3.5kb）的成分（表示为中间（M）成分）彼此以及与顶部（T）成分分离，T 成分不含任何 RNA。以前的临床前小鼠研究和犬科癌症试验使用 CPMV 的混合群体（包含 B、M 和 T 成分），因此尚不清楚粒子类型在功效上是否存在差异。已知 CPMV RNA 基因组通过激活 TLR7 来促进免疫刺激。为了确定大小不同且序列无关的两种 RNA 基因组是否引起不同的免疫刺激，我们比较了 B 和 M 成分以及未分离的 CPMV 在体外和小鼠癌症模型中的治疗功效。我们发现，分离的 B 和 M 颗粒的行为与混合的 CPMV 相似，激活先天免疫细胞诱导促炎细胞因子如 IFNα、IFNγ、IL-6 和 IL-12 的分泌，同时抑制免疫抑制细胞因子如 TGF-β和 IL-10。在黑色素瘤和结肠癌的小鼠模型中，混合和分离的 CPMV 颗粒均显著降低肿瘤生长并延长存活期，无显著差异。这表明，即使 B 颗粒比 M 颗粒多 40%的 RNA，特定的 RNA 基因组也能相似地刺激免疫系统；每种 CPMV 颗粒类型都可以用作有效的癌症佐剂，与天然混合 CPMV 具有相同的功效。从转化的角度来看，与使用混合 CPMV 制剂相比，使用 B 或 M 成分具有单独的 B 或 M 是非感染植物的优势，因此提供了农业安全。
