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Ageing is often accompanied with a decline in immune system function, resulting in immune ageing. Numerous studies have focussed on the changes in different lymphocyte subsets in diseases and immunosenescence. The change in immune phenotype is a key indication of the diseased or healthy status. However, the changes in lymphocyte number and phenotype brought about by ageing have not been comprehensively analysed. Here, we analysed T and natural killer (NK) cell subsets, the phenotype and cell differentiation states in 43,096 healthy individuals, aged 20–88 years, without known diseases. Thirty-six immune parameters were analysed and the reference ranges of these subsets were established in different age groups divided into 5-year intervals. The data were subjected to random forest machine learning for immune-ageing modelling and confirmed using the neural network analysis. Our initial analysis and machine modelling prediction showed that naïve T cells decreased with ageing, whereas central memory T cells (Tcm) and effector memory T cells (Tem) increased cluster of differentiation (CD) 28-associated T cells. This is the largest study to investigate the correlation between age and immune cell function in a Chinese population, and provides insightful differences, suggesting that healthy adults might be considerably influenced by age and sex. The age of a person's immune system might be different from their chronological age. Our immune-ageing modelling study is one of the largest studies to provide insights into ‘immune-age’ rather than ‘biological-age’. Through machine learning, we identified immune factors influencing the most through ageing and built a model for immune-ageing prediction. Our research not only reveals the impact of age on immune parameter differences within the Chinese population, but also provides new insights for monitoring and preventing some diseases in clinical practice.

Background: Intestinal flora dynamically affects the host's systemic immune system. Liver is one of the organs that may be affected by intestinal microbiota. Materials and Methods: In this study, we aimed to identify proteome level differences between liver tissue from mice cleared intestinal flora and control using tandem mass spectrometry (LC-MS/MS) and label free quantification. Additionally, protein-protein interactions were mapped by STRING, and also, the enrichment of inflammation-related signaling pathways and biological processes was identified using GO and IPA network system. RT-PCR and Western blot were used for validation of the proteomics findings. Results: Our study demonstrated that mice with cleared intestinal flora exhibited decreased sensitivity to Concanavalin A induced acute hepatitis. 324 Proteins in liver were differently expressed after intestinal flora clearance for one week while 210 proteins were differently expressed after intestinal flora clearance for two weeks. Furthermore, five of the identified proteins were validated by western blotting and further investigated by semi-quantitative RT-PCR. Conclusion: Our results showed that intestinal flora clearance in mice could reduce sensitivity to Concanavalin A induced liver injury and influence the expression of proteins in liver, which provides a clue for studying the relationship between gut bacteria and Concanavalin A induced hepatitis.

Aluminum salt (Alum) is one of the most important immune adjuvants approved for use in humans, however it is not suitable for vaccination against various chronic infectious diseases and cancers for not being able to induce cell-mediated (Th1) immunity. Here, we encapsulated an Alum colloid inside β-glucan particles (GPs), which are a type of natural particles derived from the yeast glucan shells, to prepare hybrid GP-Alum (GP-Al) adjuvant particles with a very uniform size of 2–4 μm. These hybrid particles can be used to load antigen proteins through a simple mixing procedure, and can be highly specifically targeted to antigen-presenting cells (APCs) and strongly activate dendritic cells (DCs) maturation and cytokine secretion. In an animal model, they elicit a strong Th1-biased immune response and extremely high antibody titer, and cause marked prophylactic and therapeutic effects against tumors. As Alum has been proven to be a safe adjuvant to induce strong humoral responses and β-glucans are safe for human use, this very uniform hybrid Alum particulate system could have important application as a vaccine carrier to stimulate humoral and cellular immune responses at the same time.