Moderating hypoxia and promoting immunogenic photodynamic therapy by HER-2 nanobody conjugate nanoparticles for ovarian cancer treatment

Single-domain antibodies as therapeutics for solid tumor treatment

Single-domain antibodies (sdAbs), initially identified in camelids or sharks and commonly referred to as nanobodies or VNARs, have emerged as a promising alternative to conventional therapeutic antibodies. These sdAbs have many superior physicochemical and pharmacological properties, including small size, good solubility and thermostability, easier accessible epitopes, and strong tissue penetration. However, the inherent challenges associated with the animal origin of sdAbs limit their clinical use. In recent years, various innovative humanization technologies, including complementarity-determining region (CDR) grafting or complete engineering of fully human sdAbs, have been developed to mitigate potential immunogenicity issues and enhance their compatibility. This review provides a comprehensive exploration of sdAbs, emphasizing their distinctive features and the progress in humanization methodologies. In addition, we provide an overview of the recent progress in developing drugs and therapeutic strategies based on sdAbs and their potential in solid tumor treatment, such as sdAb-drug conjugates, multispecific sdAbs, sdAb-based delivery systems, and sdAb-based cell therapy.

Nanoplatform-enhanced photodynamic therapy for the induction of immunogenic cell death

As an efficient, non-invasive, low-side-effect, and highly selective cancer therapy, photodynamic therapy (PDT) is used to treat various malignant tumors. However, the inefficiency of dealing with deep tumors and metastatic lesions highly limits the use of PDT. Immunogenic cell death (ICD) is a particular form of tumor cell death that could elicit a tumor-special immune response, leading to a systemic anti-tumor effect and providing therapeutic benefits for metastatic lesions. In this regard, it is crucial to enhance the ability of PDT to induce ICD. Luckily, advanced nanotechnology created many promising ways to improve the immunogenicity of PDT and achieve photoimmunotherapy. This review summarizes the emerging strategies for triggering immunogenic cell death via nanoplatform-enhanced PDT, with particular emphasis on their advantages in photoimmunotherapy. We highlight the nanoplatforms classified according to the basic principles of photodynamic therapy and immunogenic cell death, which provides a valuable reference for the design of nanoplatform for photoimmunotherapy. In addition, we also discuss the current situation and prospect of nano-based photoimmunotherapy in clinical studies.

Minimally invasive injection of biomimetic Nano@Microgel for in situ ovarian cancer treatment through enhanced photodynamic reactions and photothermal combined therapy

Photodynamic therapy (PDT) induces immunogenic cell death (ICD) by producing reactive oxygen species (ROS), making it an ideal method for cancer treatment. However, the extremely lower level of oxygen, short half-life of produced ROS, and limited photosensitizers accumulating in the tumor site via intravenous administration are the main reasons that limit the further application of PDT. To address these issues, we loaded the photosensitizer porphine (THPP) into biomimetic gold nanorod-mesoporous silica core-shell nanoparticles (Au-MSN NPs) to prepare Au@MSN/THPP@CM NPs. We then seeded the NPs together with catalase (CAT) into a gelatin methacryloyl (GelMA) microgel matrix to form Au@MSN-Ter/THPP@CM@GelMA/CAT microspheres consisting of biomimetic nano@microgel. The NPs and biomimetic nano@microgel exhibited enhanced photodynamic (PD) reaction and excellent photothermal conversion ability. Moreover, we further conjugated an endoplasmic reticulum (ER) targeting ligand Tosyl Ethylenediamine (Ter) on the surface of Au-MSN NPs. The results showed that both Au@MSN-Ter/THPP@CM NPs and the finally formed Au@MSN-Ter/THPP@CM@GelMA/CAT biomimetic nano@microgel induced precise and prolonged ER stress through photodynamic reactions, which stimulated the exposure of the proapoptotic calreticulin (CRT) on the cell membrane and increased the release of high mobility group box 1 (HMGB1) form the nucleus in SKOV3 cells under near-infrared (NIR) laser irradiation. Additionally, a single dose of the nano@microgel delivered through minimally invasive injection generated a significant anti-tumor effect in the SKOV3 cell line-derived orthotopic ovarian cancer mouse model through a PD and PT combination therapy. This study offers a new strategy for enhanced PDT and provides a PD/PT synergistic treatment method for ovarian cancer.

Nanobodies: Robust miniprotein binders in biomedicine

Variable domains of heavy chain-only antibodies (VHH), also known as nanobodies (Nbs), are monomeric antigen-binding domains derived from the camelid heavy chain-only antibodies. Nbs are characterized by small size, high target selectivity, and marked solubility and stability, which collectively facilitate high-quality drug development. In addition, Nbs are readily expressed from various expression systems, including E. coli and yeast cells. For these reasons, Nbs have emerged as preferred antibody fragments for protein engineering, disease diagnosis, and treatment. To date, two Nb-based therapies have been approved by the U.S. Food and Drug Administration (FDA). Numerous candidates spanning a wide spectrum of diseases such as cancer, immune disorders, infectious diseases, and neurodegenerative disorders are under preclinical and clinical investigation. Here, we discuss the structural features of Nbs that allow for specific, versatile, and strong target binding. We also summarize emerging technologies for identification, structural analysis, and humanization of Nbs. Our main focus is to review recent advances in using Nbs as a modular scaffold to facilitate the engineering of multivalent polymers for cutting-edge applications. Finally, we discuss remaining challenges for Nb development and envision new opportunities in Nb-based research.

Preparation of a Nanobody Specific to Dectin 1 and Its Anti-inflammatory Effects on Fungal Keratitis

Objective

To prepare a nanobody specific to dectin 1 and verify its specificity and anti-inflammatory effects on Aspergillus fumigatus keratitis.

Methods

The nanobody was selected from a high-quality shark-antibody library constructed with phage-display technology. The nanobody was developed in the expression systems of Escherichia coli. Indirect ELISA was used to determine the specificity of the nanobody to recombinant dectin 1 protein. The potential of the nanobody to be recognized and expressed on the surfaces of cells and corneas was detected by immunofluorescence, and its anti-inflammatory effect on A. fumigatus keratitis was further verified. After infection with A. fumigatus, eyes of C57B L/6 mice were treated with nanobodies. Human corneal epithelial cells (HCECs) were pretreated with nanobodies and then incubated with A. fumigatus. Clinical scores and slit-lamp photography were used to assess disease response in mouse corneas. RT-PCR and ELISA were used to evaluate mRNA and protein expression of IL1β and IL6 in both mouse corneas and HCECs.

Results

The nanobody was successfully expressed through microbial system and showed specific high-affinity binding to recombinant dectin 1. Furthermore, it exhibited specific binding to dectin 1 expressed on the surfaces of cells and recognized dectin 1 in mouse corneas. Importantly, it reduced clinical scores of A. fumigatus keratitis in mice compared with a PBS-treatment group. In addition, it decreased mRNA and protein expression of IL1β and IL6 in infected corneas and HCECs stimulated with A. fumigatus.

Conclusion

These results suggest that this nanobody can bring about anti-inflammatory effects. This highlights the potential of these nanobodies as innovative therapeutic agents in A. fumigatus.