Preparation and evaluation of the adjuvant effect of curdlan sulfate in improving the efficacy of dendritic cell-based vaccine for antitumor immunotherapy

The antibacterial and hemostatic curdlan hydrogel-loading epigallocatechin gallate for facilitating the infected wound healing

The infected wounds pose one of the major threats to human health today. To address this issue, it is necessary to develop innovative wound dressings with superior antibacterial activity and other properties. Due to its potent antibacterial, antioxidant, and immune-boosting properties, epigallocatechin gallate (EGCG) has been widely utilized. In this study, a multifunctional curdlan hydrogel loading EGCG (Cur-EGCGH3) was designed. Cur-EGCGH3 exhibited excellent physicochemical properties, good biocompatibility, hemostatic, antibacterial, and antioxidant activities. Also, ELISA data showed that Cur-EGCGH3 stimulated macrophages to secrete pro-inflammatory and pro-regenerative cytokines. Cell scratch results indicated that Cur-EGCGH3 promoted the migration of NIH3T3 and HUVECs. In vivo experiments confirmed that Cur-EGCGH3 could inhibit bacterial infection of the infected wounds, accelerate hemostasis, and promote epithelial regeneration and collagen deposition. These results demonstrated that Cur-EGCGH3 holds promise for promoting healing of the infected wounds.

Preparation and characterization of curdlan-chitosan conjugate nanoparticles as mucosal adjuvants for intranasal influenza H1N1 subunit vaccine

Intranasal vaccination offers crucial protection against influenza virus pandemics. However, antigens, especially subunit antigens, often fail to induce effective immune responses without the help of immune adjuvants. Our research has demonstrated that a polyelectrolyte complex, composed of curdlan sulfate/O-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (CS/O-HTCC), effectively triggers both mucosal and systemic immune responses when administrated intranasal. In this study, stable nanoparticles formed by curdlan-O-HTCC conjugate (CO NP) were prepared and characterized. Furthermore, the efficacy of CO NP was evaluated as a mucosal adjuvant in an intranasal influenza H1N1 subunit vaccine. The results revealed that CO NP exhibits uniform and spherical morphology, with a size of 190.53 ± 4.22 nm, and notably, it remains stable in PBS at 4 °C for up to 6 weeks. Biological evaluation demonstrated that CO NP stimulates the activation of antigen-presenting cells (APCs), including macrophages and dendritic cells (DCs), both in vitro and in vivo. Furthermore, intranasal administration of CO NP effectively elicits cellular and humoral immune responses, notably enhancing mucosal immunity. Thus, CO NP emerges as a promising mucosal adjuvant for influenza subunit vaccines.

Self-adjuvant Astragalus polysaccharide-based nanovaccines for enhanced tumor immunotherapy: a novel delivery system candidate for tumor vaccines

The study of tumor nanovaccines (NVs) has gained interest because they specifically recognize and eliminate tumor cells. However, the poor recognition and internalization by dendritic cells (DCs) and insufficient immunogenicity restricted the vaccine efficacy. Herein, we extracted two molecular-weight Astragalus polysaccharides (APS, 12.19 kD; APSHMw, 135.67 kD) from Radix Astragali and made them self-assemble with OVA257-264 directly forming OVA/APS integrated nanocomplexes through the microfluidic method. The nanocomplexes were wrapped with a sheddable calcium phosphate layer to improve stability. APS in the formed nanocomplexes served as drug carriers and immune adjuvants for potent tumor immunotherapy. The optimal APS-NVs were approximately 160 nm with uniform size distribution and could remain stable in physiological saline solution. The FITC-OVA in APS-NVs could be effectively taken up by DCs, and APS-NVs could stimulate the maturation of DCs, improving the antigen cross-presentation efficiency in vitro. The possible mechanism was that APS can induce DC activation via multiple receptors such as dectin-1 and Toll-like receptors 2 and 4. Enhanced accumulation of APS-NVs both in draining and distal lymph nodes were observed following s.c. injection. Smaller APS-NVs could easily access the lymph nodes. Furthermore, APS-NVs could markedly promote antigen delivery efficiency to DCs and activate cytotoxic T cells. In addition, APS-NVs achieve a better antitumor effect in established B16-OVA melanoma tumors compared with the OVA+Alum treatment group. The antitumor mechanism correlated with the increase in cytotoxic T cells in the tumor region. Subsequently, the poor tumor inhibitory effect of APS-NVs on the nude mouse model of melanoma also confirmed the participation of antitumor adaptive immune response induced by NVs. Therefore, this study developed a promising APS-based tumor NV that is an efficient tumor immunotherapy without systemic side effects.

Recent innovations (2020-2023) in the approaches for the chemical functionalization of curdlan and pullulan: A mini-review

Chemical modification represents a highly efficacious approach for enhancing the physicochemical characteristics and biological functionalities of natural polysaccharides. However, not all polysaccharides have considerable pharmacologic activity; so, appropriate chemical modification strategies can be selected in accordance with the distinct structural properties of polysaccharides to aid in improving and encouraging the presentation of their biological activities. Hence, there has been a growing interest in the chemical alteration of polysaccharides due to their various properties such as antioxidant, anticoagulant, antiviral, anticancer, biomedical, antibacterial, and immunomodulatory effects. This paper offers a comprehensive examination of recent scientific advancements produced over the past four years in the realm of unique chemical and functional modifications in curdlan and pullulan structures. This review aims to provide readers with an overview of the structural activity correlations observed in the backbone structures of curdlan and pullulan, as well as the diverse chemical modification processes employed for these polysaccharides. Additionally, the review aims to examine the effects of combining various bioactive molecules with chemically modified curdlan and pullulan and explore their potential applications in various important fields.

Lymph node and tumor-associated PD-L1+ macrophages antagonize dendritic cell vaccines by suppressing CD8+ T cells

Current immunotherapies provide limited benefits against T cell-depleted tumors, calling for therapeutic innovation. Using multi-omics integration of cancer patient data, we predict a type I interferon (IFN) responseHIGH state of dendritic cell (DC) vaccines, with efficacious clinical impact. However, preclinical DC vaccines recapitulating this state by combining immunogenic cancer cell death with induction of type I IFN responses fail to regress mouse tumors lacking T cell infiltrates. Here, in lymph nodes (LNs), instead of activating CD4+/CD8+ T cells, DCs stimulate immunosuppressive programmed death-ligand 1-positive (PD-L1+) LN-associated macrophages (LAMs). Moreover, DC vaccines also stimulate PD-L1+ tumor-associated macrophages (TAMs). This creates two anatomically distinct niches of PD-L1+ macrophages that suppress CD8+ T cells. Accordingly, a combination of PD-L1 blockade with DC vaccines achieves significant tumor regression by depleting PD-L1+ macrophages, suppressing myeloid inflammation, and de-inhibiting effector/stem-like memory T cells. Importantly, clinical DC vaccines also potentiate T cell-suppressive PD-L1+ TAMs in glioblastoma patients. We propose that a multimodal immunotherapy and vaccination regimen is mandatory to overcome T cell-depleted tumors.

Polymeric biomaterial-inspired cell surface modulation for the development of novel anticancer therapeutics

Immune cell-based therapies are a rapidly emerging class of new medicines that directly treat and prevent targeted cancer. However multiple biological barriers impede the activity of live immune cells, and therefore necessitate the use of surface-modified immune cells for cancer prevention. Synthetic and/or natural biomaterials represent the leading approach for immune cell surface modulation. Different types of biomaterials can be applied to cell surface membranes through hydrophobic insertion, layer-by-layer attachment, and covalent conjugations to acquire surface modification in mammalian cells. These biomaterials generate reciprocity to enable cell-cell interactions. In this review, we highlight the different biomaterials (lipidic and polymeric)-based advanced applications for cell-surface modulation, a few cell recognition moieties, and how their interplay in cell-cell interaction. We discuss the cancer-killing efficacy of NK cells, followed by their surface engineering for cancer treatment. Ultimately, this review connects biomaterials and biologically active NK cells that play key roles in cancer immunotherapy applications.

Progress towards Adjuvant Development: Focus on Antiviral Therapy

In recent decades, vaccines have been extraordinary resources to prevent pathogen diffusion and cancer. Even if they can be formed by a single antigen, the addition of one or more adjuvants represents the key to enhance the response of the immune signal to the antigen, thus accelerating and increasing the duration and the potency of the protective effect. Their use is of particular importance for vulnerable populations, such as the elderly or immunocompromised people. Despite their importance, only in the last forty years has the search for novel adjuvants increased, with the discovery of novel classes of immune potentiators and immunomodulators. Due to the complexity of the cascades involved in immune signal activation, their mechanism of action remains poorly understood, even if significant discovery has been recently made thanks to recombinant technology and metabolomics. This review focuses on the classes of adjuvants under research, recent mechanism of action studies, as well as nanodelivery systems and novel classes of adjuvants that can be chemically manipulated to create novel small molecule adjuvants.

Beta glucan as an immune stimulant in tumor microenvironment - Insight into lessons and promises from past decade

Cancer is characterized by a perturbed immune landscape. Inside tumor microenvironment, immune system is reprogrammed to facilitate tumor growth and survival rather than eliminating it. This immune evasive mechanism needs to be reversed to normal for effective anticancer therapeutic strategy. Immunotherapy has emerged as a novel strategy for redeployment of immune cells against cancer. However, they suffer in their efficacy, response rate and side effects. This necessitated us to turn toward natural repertoires which can act as a substitute to conventional immunotherapeutics. Beta glucan, a polysaccharide derived from mushroom, serves the role of immunomodulator inside tumor microenvironment. It acts as pathogen associated molecular pattern and bind to various pattern recognition receptors expressed on surface of immune cells thereby facilitating their activation and crosstalk. This result in resurgence of suppressed immune surveillance in the tumor milieu. In this review, we highlight in brief the advances and limitation of cancer immunotherapy. Alongside, we have discussed the detailed mechanistic principle and recent advances underlying restoration of immune functionality by beta glucan.

Display of CCL21 on cancer cell membrane through genetic modification using a pH low insertion peptide

CCL21, a secondary lymphoid tissue chemokine, plays an important role in generating an effective anti-tumor immune response. In this study, a genetically modified CCL21 was developed by inserting a pH low insertion peptide to establish a CCL21-rich microenvironment for tumors. The fusion tag thioredoxin (Trx) was designed and fused at the N-terminal of the recombinant protein to protect it from being irrevocably misfolded in microbial host cells. The prokaryotic expression vector pET32a-CCL21-pHLIP was constructed and successfully expressed in E. coli BL21 (DE3) with a soluble expression form and a molecular weight of ~35 kDa. The induction conditions were optimized to obtain an extremely high yield of 6.7 mg target protein from 31.1 mg total protein. The 6xHis tagged Trx-CCL21-pHLIP was purified using Ni-NTA resin, and it was confirmed using SDS-PAGE and Western blot analyses. Consequently, the Trx-CCL21-pHLIP protein was successfully displayed on the cancer cell surface in a weak acidic microenvironment and showed the same ability as CCL21 in recruiting CCR7-positive cells. Additionally, the CCL21 fusion protein with or without Trx tag showed similar functions. Therefore, the study implies the feasibility of directing a modular genetic method for the development of protein-based drugs.

Dendritic-Cell-Vaccine-Based Immunotherapy for Hepatocellular Carcinoma: Clinical Trials and Recent Preclinical Studies

Although many surgical and nonsurgical therapeutic options have been well-established, hepatocellular carcinoma (HCC) remains the third most common cause of cancer-related death worldwide. Therefore, the discovery of novel potential therapeutic strategies is still urgently required for improving survival and prognosis of HCC patients. As the most potent antigen-presenting cells in the human immune system, dendritic cells (DCs) play an important role in activating not only innate but also adaptive immune responses to specifically destroy tumor cells. As a result, DC-based vaccines, which are prepared by different tumor-antigen-pulsing strategies or maturation-stimulating reagents, either alone or in combination with various anticancer therapies and/or immune effector cells, have been developed as a promising personalized cancer immunotherapy. This review provides a comprehensive summary of the evidence from clinical trials evaluating the safety, feasibility, and efficacy of DC-based vaccines in treating HCC patients and highlights the data from recent preclinical studies regarding the development of promising strategies for optimizing the efficacy of DC-vaccine-based immunotherapy for HCC.

Exploiting diol reactivity for the access to unprecedented low molecular weight curdlan sulfate polysaccharides

Curdlan is a bacterial sourced polysaccharide, consisting of a linear backbone of β-1 → 3-linked glucose (Glc) units. The high interest in pharmaceutical applications of curdlan and derivatives thereof is fueling the study of multi-step sequences for regioselective modifications of its structure. Here we have developed semi-synthetic sequences based on a regioselective protection-sulfation-deprotection approach, allowing the access to some, new, low molecular weight curdlan polysaccharide derivatives with unprecedented sulfation patterns. Three different semi-synthetic schemes were investigated, all relying upon the installation of a cyclic benzylidene protecting group on Glc O-4,6-diols, followed by either direct sulfation and deprotection, or some additional steps - including a hydrolytic or oxidative cleavage of the benzylidene rings - prior to sulfation and deprotection. The six obtained polysaccharides were subjected to a detailed structural characterization by 2D-NMR analysis, revealing that some of them showed the majority of Glc units along the polymeric backbone decorated by unprecedented sulfation motifs.

Polysaccharide-based nanomedicines for cancer immunotherapy: A review

Cancer immunotherapy is an effective antitumor approach through activating immune systems to eradicate tumors by immunotherapeutics. However, direct administration of "naked" immunotherapeutic agents (such as nucleic acids, cytokines, adjuvants or antigens without delivery vehicles) often results in: (1) an unsatisfactory efficacy due to suboptimal pharmacokinetics; (2) strong toxic and side effects due to low targeting (or off-target) efficiency. To overcome these shortcomings, a series of polysaccharide-based nanoparticles have been developed to carry immunotherapeutics to enhance antitumor immune responses with reduced toxicity and side effects. Polysaccharides are a family of natural polymers that hold unique physicochemical and biological properties, as they could interact with immune system to stimulate an enhanced immune response. Their structures offer versatility in synthesizing multifunctional nanocomposites, which could be chemically modified to achieve high stability and bioavailability for delivering therapeutics into tumor tissues. This review aims to highlight recent advances in polysaccharide-based nanomedicines for cancer immunotherapy and propose new perspectives on the use of polysaccharide-based immunotherapeutics.

A purified acidic polysaccharide from Sarcandra glabra as vaccine adjuvant to enhance anti-tumor effect of cancer vaccine

Immunological adjuvants are an important part of tumor vaccines and are critical for stimulating anti-tumor immune responses. However, the clinical needs of strong adjuvants have not been met. In this work, we found that the purified acidic polysaccharide from Sarcandra glabra, named p-SGP, is an ideal adjuvant for tumor vaccines. Cancer vaccines could induce stronger humoral and cellular immune responses when they are adjuvanted with p-SGP. Compared with CpG, a well-studied adjuvant, p-SGP significantly augmented the anti-tumor immunity of various cancer vaccines, which is leading to noticeable inhibition of tumor growth and metastasis in tumor-bearing mice. Moreover, p-SGP promoted dendritic cells (DCs) maturation and Th1-polarized immune response. Toll-like receptor 4 (TLR4) inhibitor TAK-242 could significantly inhibit the expression of mature molecules on the surface of DCs stimulated by p-SGP, suggesting that p-SGP could play the role of activating DCs through the TLR4 receptor. Results of RNA-seq showed that the Delta-like ligand 4 (DLL4) gene in the pathway Th1 and Th2 cell differentiation was significantly up-regulated in the DCs treated with p-SGP, suggesting that p-SGP has a unique mechanism of enhancing anti-tumor immunity.

Nanomedicine Approach to Immunotherapy of Hepatocellular Carcinoma

In recent years, the growing studies focused on the immunotherapy of hepatocellular carcinoma and proved the preclinical and clinical promises of host antitumor immune response. However, there were still various obstacles in meeting satisfactory clinic need, such as low response rate, primary resistance and secondary resistance to immunotherapy. Tackling these barriers required a deeper understanding of immune underpinnings and a broader understanding of advanced technology. This review described immune microenvironment of liver and HCC which naturally decided the complexity of immunotherapy, and summarized recent immunotherapy focusing on different points. The ever-growing clues indicated that the instant killing of tumor cell and the subsequent relive of immunosuppressive microenvironment were both indis- pensables. The nanotechnology applied in immunotherapy and the combination with intervention technology was also discussed.

TLR Agonists as Mediators of Trained Immunity: Mechanistic Insight and Immunotherapeutic Potential to Combat Infection

Despite advances in critical care medicine, infection remains a significant problem that continues to be complicated with the challenge of antibiotic resistance. Immunocompromised patients are highly susceptible to development of severe infection which often progresses to the life-threatening condition of sepsis. Thus, immunotherapies aimed at boosting host immune defenses are highly attractive strategies to ward off infection and protect patients. Recently there has been mounting evidence that activation of the innate immune system can confer long-term functional reprogramming whereby innate leukocytes mount more robust responses upon secondary exposure to a pathogen for more efficient clearance and host protection, termed trained immunity. Toll-like receptor (TLR) agonists are a class of agents which have been shown to trigger the phenomenon of trained immunity through metabolic reprogramming and epigenetic modifications which drive profound augmentation of antimicrobial functions. Immunomodulatory TLR agonists are also highly beneficial as vaccine adjuvants. This review provides an overview on TLR signaling and our current understanding of TLR agonists which show promise as immunotherapeutic agents for combating infection. A brief discussion on our current understanding of underlying mechanisms is also provided. Although an evolving field, TLR agonists hold strong therapeutic potential as immunomodulators and merit further investigation for clinical translation.

Current Trends in Cancer Immunotherapy

The search for an effective drug to treat oncological diseases, which have become the main scourge of mankind, has generated a lot of methods for studying this affliction. It has also become a serious challenge for scientists and clinicians who have needed to invent new ways of overcoming the problems encountered during treatments, and have also made important discoveries pertaining to fundamental issues relating to the emergence and development of malignant neoplasms. Understanding the basics of the human immune system interactions with tumor cells has enabled new cancer immunotherapy strategies. The initial successes observed in immunotherapy led to new methods of treating cancer and attracted the attention of the scientific and clinical communities due to the prospects of these methods. Nevertheless, there are still many problems that prevent immunotherapy from calling itself an effective drug in the fight against malignant neoplasms. This review examines the current state of affairs for each immunotherapy method, the effectiveness of the strategies under study, as well as possible ways to overcome the problems that have arisen and increase their therapeutic potentials.