Mannan Derivatives Instruct Dendritic Cells to Induce Th1/Th2 Cells Polarization via Differential Mitogen-Activated Protein Kinase Activation

Fungal vaccines and adjuvants: a tool to reveal the interaction between host and fungi

Fungal infections are incurring high risks in a range from superficial mucosal discomforts (such as oropharyngeal candidiasis and vulvovaginal candidiasis) to disseminated life-threatening diseases (such as invasive pulmonary aspergillosis and cryptococcal meningitis) and becoming a global health problem in especially immunodeficient population. The major obstacle to conquer fungal harassment lies in the presence of increasing resistance to conventional antifungal agents used in newly clinically isolated strains. Although recombinant cytokines and mono-/poly-clonal antibodies are added into antifungal armamentarium, more effective antimycotic drugs are exceedingly demanded. It is comforting that the development of fungal vaccines and adjuvants opens up a window to brighten the prospective way in the diagnosis, prevention and treatment of fungal assaults. In this review, we focus on the progression of several major fungal vaccines devised for the control of Candida spp., Aspergillus spp., Cryptococcus spp., Coccidioides spp., Paracoccidioides spp., Blastomyces spp., Histoplasma spp., Pneumocystis spp. as well as the adjuvants adopted. We then expound the interaction between fungal vaccines/adjuvants and host innate (macrophages, dendritic cells, neutrophils), humoral (IgG, IgM and IgA) and cellular (Th1, Th2, Th17 and Tc17) immune responses which generally experience immune recognition of pattern recognition receptors, activation of immune cells, and clearance of invaded fungi. Furthermore, we anticipate an in-depth understanding of immunomodulatory properties of univalent and multivalent vaccines against diverse opportunistic fungi, providing helpful information in the design of novel fungal vaccines and adjuvants.

Recent Advances in Biomedical Applications of Mannans and Xylans

Plant-based phytochemicals, including flavonoids, alkaloids, tannins, saponins, and other metabolites, have attracted considerable attention due to their central role in synthesizing nanomaterials with various biomedical applications. Hemicelluloses are the second most abundant among naturally occurring heteropolymers, accounting for one-third of all plant constituents. In particular, xylans, mannans, and arabinoxylans are structured polysaccharides derived from hemicellulose. Mannans and xylans are characterized by their linear configuration of β-1,4-linked mannose and xylose units, respectively. At the same time, arabinoxylan is a copolymer of arabinose and xylose found predominantly in secondary cell walls of seeds, dicotyledons, grasses, and cereal tissues. Their widespread use in tissue engineering, drug delivery, and gene delivery is based on their properties, such as cell adhesiveness, cost-effectiveness, high biocompatibility, biodegradability, and low immunogenicity. Moreover, it can be easily functionalized, which expands their potential applications and provides them with structural diversity. This review comprehensively addresses recent advances in the field of biomedical applications. It explores the potential prospects for exploiting the capabilities of mannans and xylans in drug delivery, gene delivery, and tissue engineering.

Dendritic Cells and Their Immunotherapeutic Potential for Treating Type 1 Diabetes

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells through a process that is primarily mediated by T cells. Emerging evidence suggests that dendritic cells (DCs) play a crucial role in initiating and developing this debilitating disease. DCs are professional antigen-presenting cells with the ability to integrate signals arising from tissue infection or injury that present processed antigens from these sites to naïve T cells in secondary lymphoid organs, thereby triggering naïve T cells to differentiate and modulate adaptive immune responses. Recent advancements in our knowledge of the various subsets of DCs and their cellular structures and methods of orchestration over time have resulted in a better understanding of how the T cell response is shaped. DCs employ various arsenal to maintain their tolerance, including the induction of effector T cell deletion or unresponsiveness and the generation and expansion of regulatory T cell populations. Therapies that suppress the immunogenic effects of dendritic cells by blocking T cell costimulatory pathways and proinflammatory cytokine production are currently being sought. Moreover, new strategies are being developed that can regulate DC differentiation and development and harness the tolerogenic capacity of these cells. Here, in this report, we focus on recent advances in the field of DC immunology and evaluate the prospects of DC-based therapeutic strategies to treat T1D.

Research Progress on the Mechanism of Natural Product Ingredients in the Treatment of Uveitis

Background

As the spectrum of ophthalmic diseases keeps changing, uveitis has gradually become one of the major blinding eye diseases in the world. In recent years, it has become a research hotspot to select effective components for uveitis treatment from natural drugs.

Methods

We searched PubMed and EMBASE databases for studies written in English as well as Chinese National Knowledge Infrastructure (CNKI), CQVIP, and Wan Fang database for studies written in Chinese (inception through 30 December 2020).

Results

Eight kinds of natural product ingredients were included in this article. They were found to not only regulate the expression of cytokines, proliferation, and differentiation of T help cells but also inhibit the damage of cytokines and inflammatory cells to uvea, blood aqueous barrier, and blood retinal barrier.

Conclusion

Natural product ingredients have their unique advantages in the treatment of uveitis. They have good anti-inflammatory effects without causing serious adverse reactions, which enables them to be promising choices for preventive and therapeutic strategy of uveitis.

Role of dendritic cells in the host response to biomaterials and their signaling pathways

Strategies to enhance, inhibit, or qualitatively modulate immune responses are important for diverse biomedical applications such as vaccine adjuvant, drug delivery, immunotherapy, cell transplant, tissue engineering, and regenerative medicine. However, the clinical efficiency of these biomaterial systems is affected by the limited understanding of their interaction with complex host microenvironments, for example, excessive foreign body reaction and immunotoxicity. Biomaterials and biomedical devices implanted in the body may induce a highly complicated and orchestrated series of host responses. As macrophages are among the first cells to infiltrate and respond to implanted biomaterials, the macrophage-mediated host response to biomaterials has been well studied. Dendritic cells (DCs) are the most potent antigen-presenting cells that activate naive T cells and bridge innate and adaptive immunity. The potential interaction of DCs with biomaterials appears to be critical for exerting the function of biomaterials and has become an important, developing area of investigation. Herein, we summarize the effects of the physicochemical properties of biomaterials on the immune function of DCs together with their receptors and signaling pathways. This review might provide a complete understanding of the interaction of DCs with biomaterials and serve as a reference for the design and selection of biomaterials with particular effects on targeted cells. STATEMENT OF SIGNIFICANCE: Biomaterials implanted in the body are increasingly applied in clinical practice. The performance of these implanted biomaterials is largely dependent on their interaction with the host immune system. As antigen-presenting cells, dendritic cells (DCs) directly interact with biomaterials through pattern recognition receptors (PRRs) recognizing "biomaterial-associated molecular patterns" and generate a battery of immune responses. In this review, the physicochemical properties of biomaterials that regulate the immune function of DCs together with their receptors and signaling pathways of biomaterial-DC interactions are summarized and discussed. We believe that knowledge of the interplay of DC and biomaterials may spur clinical translation by guiding the design and selection of biomaterials with particular effects on targeted cell for tissue engineering, vaccine delivery, and cancer therapy.

Cigarette Smoke Extract Promotes TIM4 Expression in Murine Dendritic Cells Leading to Th2 Polarization through ERK-Dependent Pathways

Smoking is considered to be the main source of indoor pollution, and it has been identified as an important environmental factor contributing to asthma onset. We know that T helper 2 (Th2) response plays a crucial role in the process of asthma disease. We have investigated the reaction of cigarette smoke extract (CSE) on Th polarization which is controlled by dendritic cells (DCs). Stimulated by CSE, immature DCs from murine bone marrow showed upregulated levels of TIM4. Cocultured with CD4+ T cells, stimulated DCs increased the ratio of IL-4+ versus IFN-γ+ of CD4+ T cells. This suggests a differentiation towards Th2 response. Moreover, antibodies against TIM4 reversed the upexpression of the IL-4+/IFN-γ+ ratio provoked by CSE, indicating that the Th2 polarization which was induced by CSE is via TIM4 mechanisms. CSE could activate mitogen-activated protein kinase pathways like ERK and p38. Upregulation of TIM4 expression by CSE stimulation was found to be inhibited by an ERK inhibitor but not p38 and JNK. In conclusion, DC-induced Th2 polarization is a hallmark of CSE allergy, and this aspect can be explained by CSE-induced TIM4 expression.

Pir-B inhibits the DC function and disturbs the Th17/Treg balance in lung cancer murine model

Paired immunoglobulin-like receptor B (Pir-B) was an inhibitory receptor expressed on the surfaces of dendritic cells (DCs). Pir-B inhibit T helper (Th) 1 response and induce Th2 cell differentiation, leading to the imbalance of Th1/Th2 cells. However, the role and potential mechanism of Pir-B on the balance of Th17/regulatory T cells (Tregs) is still largely unknown in lung cancer murine model. In the present study, the DC function and Th17/Treg balance were destroyed during the progression of lung cancer and this was accompanied by an increased expression of Pir-B. After transfection with Pir-B siRNA or administration of IL-6 in vitro, the decreased response of Th17 cells were restored, whereas the augmented differentiation of Tregs was diminished. Further, the transfer of Pir-B silenced DCs or the injection of IL-6 in vivo increased Th17 response and decreased Treg differentiation. Our study has demonstrated that Pir-B inhibits the DC function and disturbs the Th17/Treg balance via IL-6 pathway during the progression of lung cancer, contributing to inhibited antitumor immunity.

Targeting cells of the immune system: mannosylated HPMA–LMA block-copolymer micelles for targeting of dendritic cells

Background: Successful tumor immunotherapy depends on the induction of strong and sustained tumor antigen-specific immune responses by activated antigen-presenting cells (APCs) such as dendritic cells (DCs). Since nanoparticles have the potential to codeliver tumor-specific antigen and DC-stimulating adjuvant in a DC-targeting manner, we wanted to assess the suitability of mannosylated HPMA-LMA block polymers for immunotherapy. Materials & methods: Fluorescence-labeled block copolymer micelles derived from P(HPMA)-block-P(LMA) copolymers and according statistical copolymers were synthesized via RAFT polymerization, and loaded with the APC activator L18-MDP. Both types of copolymers were conjugated with D-mannose to target the mannose receptor as expressed by DCs and macrophages. The extent and specificity of micelle binding and activation of APCs was monitored using mouse spleen cells and bone marrow-derived DC (BMDC). Results: Nontargeting HPMA-LMA statistical copolymers showed strong unspecific cell binding. HPMA-LMA block copolymers bound DC only when conjugated with mannose, and in a mannose receptor-specific manner. Mannosylated HPMA-LMA block copolymers were internalized by DC. DC-targeting HPMA-LMA block copolymers mediated DC activation when loaded with L18-MDP. Conclusion: Mannosylated HPMA-LMA block copolymers are a promising candidate for the delvopment of DC-targeting nanovaccines.

Potential of nanoparticles for allergen-specific immunotherapy - use of silica nanoparticles as vaccination platform

INTRODUCTION

Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field. Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized. Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.