Enhancement of subunit vaccine delivery with zinc-carnosine coordination polymer through the addition of mannan

Vaccines represent a pivotal health advancement for preventing infection. However, because carrier systems with repeated administration can invoke carrier-targeted immune responses that diminish subsequent immune responses (e.g., PEG antibodies), there is a continual need to develop novel vaccine platforms. Zinc carnosine microparticles (ZnCar MPs), which are composed of a one-dimensional coordination polymer formed between carnosine and the metal ion zinc, have exhibited efficacy in inducing an immune response against influenza. However, ZnCar MPs' limited suspendability hinders clinical application. In this study, we address this issue by mixing mannan, a polysaccharide derived from yeast, with ZnCar MPs. We show that the addition of mannan increases the suspendability of this promising vaccine formulation. Additionally, since mannan is an adjuvant, we illustrate that the addition of mannan increases the antibody response and T cell response when mixed with ZnCar MPs. Mice vaccinated with mannan + OVA/ZnCar MPs had elevated serum IgG and IgG1 levels in comparison to vaccination without mannan. Moreover, in the mannan + OVA/ZnCar MPs vaccinated group, mucosal washes demonstrated increased IgG, IgG1, and IgG2c titers, and antigen recall assays showed enhanced IFN-γ production in response to MHC-I and MHC-II immunodominant peptide restimulation, compared to the vaccination without mannan. These findings suggest that the use of mannan mixed with ZnCar MPs holds potential for subunit vaccination and its improved suspendability further promotes clinical translation.

Immunogenicity of an adjuvanted broadly active influenza vaccine in immunocompromised and diverse populations

Influenza virus outbreaks are a major burden worldwide each year. Current vaccination strategies are inadequate due to antigenic drift/shift of the virus and the elicitation of low immune responses. The use of computationally optimized broadly reactive antigen (COBRA) hemagglutinin (HA) immunogens subvert the constantly mutating viruses; however, they are poorly immunogenic on their own. To increase the immunogenicity of subunit vaccines such as this, adjuvants can be delivered with the vaccine. For example, agonists of the stimulator of interferon genes (STING) have proven efficacy as vaccine adjuvants. However, their use in high-risk populations most vulnerable to influenza virus infection has not been closely examined. Here, we utilize a vaccine platform consisting of acetalated dextran microparticles loaded with COBRA HA and the STING agonist cyclic GMP-AMP. We examine the immunogenicity of this platform in mouse models of obesity, aging, and chemotherapy-induced immunosuppression. Further, we examine vaccine efficacy in collaborative cross mice, a genetically diverse population that mimics human genetic heterogeneity. Overall, this vaccine platform had variable efficacy in these populations supporting work to better tailor adjuvants to specific populations.

Particle-Based therapies for antigen specific treatment of type 1 diabetes

Type 1 diabetes mellitus (T1D) is the leading metabolic disorder in children worldwide. Over time, incidence rates have continued to rise with 20 million individuals affected globally by the autoimmune disease. The current standard of care is costly and time-consuming requiring daily injections of exogenous insulin. T1D is mediated by autoimmune effector responses targeting autoantigens expressed on pancreatic islet β-cells. One approach to treat T1D is to skew the immune system away from an effector response by taking an antigen-specific approach to heighten a regulatory response through a therapeutic vaccine. An antigen-specific approach has been shown with soluble agents, but the effects have been limited. Micro or nanoparticles have been used to deliver a variety of therapeutic agents including peptides and immunomodulatory therapies to immune cells. Particle-based systems can be used to deliver cargo into the cell and microparticles can passively target phagocytic cells. Further, surface modification and controlled release of encapsulated cargo can enhance delivery over soluble agents. The induction of antigen-specific immune tolerance is imperative for the treatment of autoimmune diseases such as T1D. This review highlights studies that utilize particle-based platforms for the treatment of T1D.