Functionalized nanomaterials targeting NLRP3 inflammasome driven immunomodulation: Friend or Foe

The advancement in drug delivery systems in recent times has significantly enhanced therapeutic effects by enabling site-specific targeting through nanocarriers. These nanocarriers serve as invaluable tools for pharmacotherapeutic advancements against various disorders that enhance the effectiveness of encapsulated drugs by reducing their toxicity and increasing the efficacy of less potent drugs, thereby improving the therapeutic index. Inflammasomes, protein complexes located in the activated immune cell cytoplasm, regulate the activation of caspases involved in inflammation. However, aberrant activation of inflammasomes can result in uncontrolled tissue responses, contributing to the development of various diseases. Therefore, achieving a precise balance between inflammasome inhibition and activation is crucial for effectively treating inflammatory disorders through targeted functionalized nanocarriers. Despite the wealth of available data on the relevance of functionalized nanocarriers in inflammatory disorders, the nanotechnological potential to modulate inflammasomes has not been adequately explored. In this comprehensive review, we highlight the latest research on the modulation of the inflammasome cascade, both upregulating and downregulating its function, using nanocarriers in the context of inflammatory disorders. The utilization of nanocarriers as a therapeutic strategy holds immense potential for researchers aiming to effectively target and modulate inflammasomes in the treatment of inflammatory disorders, thus improving disease severity outcomes.

Core Hydrophobicity of Supramolecular Nanoparticles Induces NLRP3 Inflammasome Activation

Designer nanomaterials capable of delivering immunomodulators to specific immune cells have been extensively studied. However, emerging evidence suggests that several of these nanomaterials can nonspecifically activate NLRP3 inflammasomes, an intracellular multiprotein complex controlling various immune cell functions, leading to undesirable effects. To understand what nanoparticle attributes activate inflammasomes, we designed a multiparametric polymer supramolecular nanoparticle system to modulate various surface and core nanoparticle-associated molecular patterns (NAMPs), one at a time. We also investigated several underlying signaling pathways, including lysosomal rupture-cathepsin B maturation and calcium flux-mitochondrial ROS production, to gain mechanistic insights into NAMPs-mediated inflammasome activation. Here, we report that out of the four NAMPs tested, core hydrophobicity strongly activates and positively correlates with the NLRP3 assembly compared to surface charge, core rigidity, and surface hydrophobicity. Moreover, we demonstrate different signaling inclinations and kinetics followed by differential core hydrophobicity patterns with the most hydrophobic ones exhibiting both lysosomal rupture and calcium influx early on. Altogether, this study will help design the next generation of polymeric nanomaterials for specific regulation of inflammasome activation, aiding efficient immunotherapy and vaccine delivery.

Characterization and analytical development for amphiphilic poly(γ-glutamic acid) as raw material of nanoparticle adjuvants

Amphiphilic graft copolymer consisting of poly(γ-glutamic acid) (γ-PGA) as the hydrophilic backbone and L-phenylalanine ethyl ester (Phe) as the hydrophobic side chain is an important biodegradable polymer with great potential in medical applications. In this research, we established analytical methods for the characterization and quality control of γ-PGA-graft-Phe (γ-PGA-Phe), which forms nanoparticles in aqueous solution, as a deployment platform in practical applications for vaccine adjuvants. The SEC-RI/MALS system, which uses size exclusion chromatography (SEC) coupled with a multi_angle light scattering (MALS) detector and refractive index (RI) detector, was developed to evaluate the characteristics of various types of polymers. By this method, it was indicated that absolute molecular weight (MW) should be used to measure the branch polymer. A gradient reversed phase HPLC (RP-HPLC) method was developed for the content of γ-PGA-Phe and the impurity levels to control product quality and safety. This quantitative approach could become key elements for identifying and characterizing γ-PGA-Phe. In addition, the degradation mechanism of γ-PGA-Phe was also identified as cleavage of main-chain of γ-PGA-Phe based on the stability study of γ-PGA-Phe in buffer solution with various pH values. The analytical developments described above will be important for use in both characterization and formulation design of biopolymers. Nanoparticles (NPs) composed of well-characterized biodegradable γ-PGA-Phe are expected to have a variety of potential clinical applications such as their use as drug and vaccine carriers.

Effect of Hydrophobic Side Chains in the Induction of Immune Responses by Nanoparticle Adjuvants Consisting of Amphiphilic Poly(γ-glutamic acid)

The new generation vaccines are safe but poorly immunogenic, and thus they require the use of adjuvants. Adjuvants that can control the balance and induction level of cellular and humoral immunities are urgently required for the treatment of and/or protection from infectious diseases and cancers. However, there are no adjuvants which can achieve these requirements. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA) with various kinds of hydrophobic amino acid ethyl esters (AAE) was synthesized (γ-PGA-AAE) and used to prepare antigen-encapsulated nanoparticles (NPs). γ-PGA-graft-Leu (γ-PGA-Leu, where Leu = leucine ethyl ester), γ-PGA-graft-Phe (γ-PGA-Phe, where Phe = phenylalanine ethyl ester), and γ-PGA-graft-Trp (γ-PGA-Trp, where Trp = tryptophan ethyl ester) formed monodispersed NPs that encapsulated ovalbumin (OVA). The type and the induction level of the antigen-specific cellular and humoral immunities could be controlled by the kinds of hydrophobic segments and vaccine formulation (encapsulation or mixture) used. When OVA was encapsulated into NPs, the cellular immunity was dominantly induced, while humoral immunity was dominant when OVA was mixed with NPs. These results are a first report to demonstrate that the balance and induction level of cellular and humoral immunities could be controlled by modifying compositions of NPs and vaccine formulation. Our results suggest that γ-PGA-AAE NPs can provide safe and efficient nanoparticle-based vaccine adjuvants, and the results also provide guidelines in the rational design of amphiphilic polymers as vaccine adjuvants which can control the balance of immune responses.