The immune response after split inactivated A/PR8 vaccine differed between asthma and naïve mice, particularly in terms of antibody activity and T cell populations. This study enhances our understanding of how asthma status may influence the effectiveness of influenza vaccine and offers insights into the AddaVax™-induced eosinophilic inflammation, guiding the development of virus vaccine strategies for both healthy individuals and asthma patients.

Asthma induction in mice results in the exhaustion of T-cell immunity, which may contribute to the defective capacity of viral protection. This study demonstrates a correlation between asthma conditions and viral susceptibility by investigating the functional characteristics of T-cells in asthma. Our results provide insights into the development of strategies to overcome the dangers of respiratory viral disease in patients with asthma.

Abstract Obesity is a known risk factor for impaired immune responses and reduced vaccine efficacy. Individuals with obesity-related metabolic disorders face heightened vulnerability to influenza, underscoring the urgent need to optimize vaccine strategies for this population. We investigated the immunological and metabolic outcomes of different influenza vaccine formulations in a diet-induced obese (DIO) mouse model. Specifically, we compared the effects of high-dose versus squalene-adjuvanted vaccines on humoral immunity, protection against viral challenge, and glucose metabolism. High-dose vaccination failed to induce robust virus-specific antibodies or sustain long-lived plasma cells in the bone marrow following infection. In contrast, squalene-adjuvanted vaccines significantly enhanced antibody responses and conferred superior protection. However, this immune enhancement was accompanied by aggravated hyperglycemia in obese mice, indicating a potential immunometabolic trade-off. Adjuvanted influenza vaccines may improve immune efficacy in obesity, but at the cost of worsening glycemic control. These findings highlight the importance of personalized vaccination approaches that account for metabolic status and immunometabolic interactions in vulnerable populations.

The use of MPL and poly I:C as adjuvants in EIV vaccines significantly improved immune responses by enhancing humoral immunity, memory cell responses, and antigen-specific cellular immunity.

Natural killer (NK) cells, which are key components of the innate immune response, are crucial for ensuring the efficacy of vaccines as they rapidly eliminate infected cells and enhance the adaptive immune response, ensuring robust and lasting protection. In this report, we investigated the effect of <i>Cladophora wrightiana</i> var. <i>minor</i> (CW) extract, a marine alga, in activating NK cells, as an adjuvant to inactivated A/Puerto Rico/8/34 H1N1 influenza vaccine (iPR8). In vitro, CW extract significantly enhanced the level of activation markers CD69 and CD107a on NK cells and triggered intracellular secretion of interferon gamma (IFN-γ) and granzyme B (GrB), indicating effective NK cell stimulation and cytotoxic function. In vivo, CW extract promoted substantial NK cell recruitment and activation, resulting in higher NK cell populations and elevated post-immunization levels of activation markers. Additionally, CW extract increased IFN-γ and GrB production in CD8⁺ T cells, highlighting its broader impact on the immune response. We also found direct evidence that CW-activated NK cells and dendritic cells (DCs) interacted with and induced the activation of immature DCs and resting NK cells, respectively. These findings suggest that CW extract is a promising adjuvant for nasal vaccines, enhancing cellular immunity by activating NK cells and supporting interactions with DCs and CD8⁺ T cells.

An effective respiratory syncytial virus (RSV) vaccine should elicit neutralizing Abs and confer protection without causing vaccine-enhanced disease. Virus-like particle (VLP) is a safe vaccine platform that can display multivalent Ags similar to a virus and induce potent neutralizing Abs without adjuvant. We investigated the impact of mutations in the furin cleavage site, fusion (F) peptide, and change in the transmembrane (TM) domain of RSV F protein in VLPs on inducing RSV neutralizing Abs and efficacy in a cotton rat model. Palivizumab-binding antigenic site II epitope was preferentially exposed by combination mutations in the furin cleavage sites and F peptide together with a change in the TM domain. A single dose of mutant F protein VLP containing these combination mutations effectively induced IgG Ab responses to post-F and pre-F proteins, neutralizing activities, and protection without apparent lung histopathology. The VLP also induced the highest level of INF-γ, indicating the Th1-skewed immune response against the virus infection. A single dose of RSV F mutant exposing an antigenic site II on VLP vaccine could induce RSV-neutralizing Abs, conferring protection without causing vaccine-enhanced disease in cotton rats.

Lactobacillus johnsonii is a commensal bacterium isolated from the vaginal and gastrointestinal tracts of vertebrate hosts, including humans. It is a potential anti-inflammatory bacterium. As reported in many animal studies, L. johnsonii supplementation reduces inflammation in the intestine and enhances the epithelial barrier. However, in this study, we observed immunostimulatory effects of heat-killed L. johnsonii JERA01 (LJ) supplementation on antigen-presenting cells, such as dendritic cells and macrophages, in mice. LJ pretreatment increased the expression of maturation markers and TNF-α, IL-6, IL-12p40 production in bone marrow-derived dendritic cells and macrophages (BMDCs and BMDMs). Co-culture of LJ-pretreated BMDCs or BMDMs with lymphocytes enhanced IFN-γ production in vitro. Oral LJ (108 CFU) supplementation induced macrophage infiltration into the peritoneal cavity and Peyer's patch at 12-h after administration, resulting in an increase in the population of IFN-γ-producing T cells in the Peyer's patch. Our investigation revealed the effects of LJ, which activates macrophages and increases the Th-1 T cell population in the intestine, implying the possibility of using L. johnsonii as an immune stimulator.

The immune response after split inactivated A/PR8 vaccine differed between asthma and naïve mice, particularly in terms of antibody activity and T cell populations. This study enhances our understanding of how asthma status may influence the effectiveness of influenza vaccine and offers insights into the AddaVax™-induced eosinophilic inflammation, guiding the development of virus vaccine strategies for both healthy individuals and asthma patients.