Molecular immunology最新文献

Background

The prevalence of food allergies is on the rise, posing a significant challenge to public health. Rodents serve as the predominant animal model in food allergy research; yet, the application of rodent models proves to be a laborious and time-consuming endeavor. It is imperative to develop novel in vivo models.

Methods

Ovalbumin (OVA) was administered as the allergen, following the recommended dosage used in other species. During the sensitization phase, a dosage of 0.25 mg per 10 tails per 1 L was administered twice daily, and during the challenge phase, the dosage was increased to 3 times the initial level. The study explored two dimensions of sensitization: the mode of exposure, which can be either continuous or intermittent, and the duration of exposure, which includes 3 days, 5 days, and 7 days. We examined midgut pathological changes, immunoglobulins contents, and mRNA expressions associated to T helper cells (Th) 2 cytokines following exposure.

Results

A significant 109.3 % increase in the number of eosinophils was observed in the midgut histopathology following intermittent 5-day OVA exposure, which emerged as the most effective model. OVA exposure increased concentrations of immunoglobulin M (IgM) (105.2 %), IgZ (312.1 %), and IgD (304.3 %) in this model. The mRNA expressions of Th2-related interleukin (IL)-4 and IL-13 were also elevated by 132.8 % and 421.0 %, respectively.

Conclusion

The intermittent 5-day OVA exposure was suggested to be the best constructed zebrafish food allergy model, which may be a potential tool for research into food allergies.

Antimicrobial peptides (AMPs) are a promising alternative to antibiotics in the fight against multi-drug resistant and immune system-evading bacterial infections. Protegrins are porcine cathelicidins which have been identified in porcine leukocytes. Protegrin-1 is the best characterized family member and has broad antibacterial activity by interacting and permeabilizing bacterial membranes. Many host defense peptides (HDPs) like LL-37 or chicken cathelicidin 2 (CATH-2) have also been shown to have protective biological functions during infections. In this regard, it is interesting to study if Protegrin-1 has the immune modulating potential to suppress unnecessary immune activation by neutralizing endotoxins or by influencing the macrophage functionality in addition to its direct antimicrobial properties. This study showed that Protegrin-1 neutralized lipopolysaccharide- (LPS) and bacteria-induced activation of RAW macrophages by binding and preventing LPS from cell surface attachment. Furthermore, the peptide treatment not only inhibited bacterial phagocytosis by murine and porcine macrophages but also interfered with cell surface and intracellular bacterial survival. Lastly, Protegrin-1 pre-treatment was shown to inhibit the amastigote survival in Leishmania infected macrophages. These experiments describe an extended potential of Protegrin-1’s protective role during microbial infections and add to the research towards clinical application of cationic AMPs.

Tanshinone I (Tan I) has been proven to exert an anti-inflammatory effect, but the complete mechanism remains unclear. In this study, Tan I was described to have no effect on Syk expression in resting or LPS-stimulated macrophages ex vivo, but dramatically suppressed Syk phosphorylation and CD80, CD86, and IL-1β expression of macrophages. The inflammatory activity of macrophages in ApoC3-transgenic (ApoC3^TG) mice is upregulated by Syk activation. Tan I was determined to downregulate Syk phosphorylation and inflammatory activity of macrophages in ApoC3^TG mice, both ex vivo and in vivo. Intraperitoneal injection of Tan I (4 mg/kg) effectively alleviated DSS-induced colitis in mice, accompanying with suppressing the activation of intestinal macrophages. Mechanistically, Tan I-treated macrophages exhibited a decrease in cytoplasmic ROS, NLRP3, GSDMD, and IL-1β, which suggested that the alternative pathway of inflammasome activation in macrophages was suppressed. The SPR assay demonstrated that Tan I bound to Syk protein with a dissociation constant (KD) of 2.473 × 10⁻⁶ M. When Syk expression was knocked down by its shRNA, the inhibitory effects of Tan I on macrophages were blocked. Collectively, Tanshinone I effectively alleviated DSS-induced colitis in mice by inhibiting Syk-stimulated inflammasome activation, hence suppressing the inflammatory activity of macrophages.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that mainly affects the joints. Studies have shown that memory CD4⁺ T cells play an important role in the pathogenesis of RA. This study investigated the expression and function of CD305 on human memory CD4⁺ T cells and the effects of CD305 activating antibody on collagen-induced arthritis. The results showed that CD305 expression was significantly decreased on circulating memory CD4⁺ T cells from patients with RA and its mean fluorescence intensity (MFI) was negatively correlated with DAS28. Moreover, CD305 inhibited the activation of memory CD4⁺ T cells by down-regulating CD69 and CD25 and the production of IFN-γ, IL-4, and IL-17A induced by anti-CD3/CD28 antibodies. In addition, activation of CD305 inhibited the severity of disease in collagen-induced arthritis. In summary, CD305 reduction may mediate the excessive activation of memory CD4⁺ T cells and participate in the development of RA. It can be used as a predictive marker of disease activity and has potential medicinal value in the treatment of RA.

Background

The treatment of food allergy (FA) needs improvement. The treatment of immune disorders can be improved by regulating epigenetic marks, which is a promising method. The objective of this research is to alleviate experimental FA by employing an inhibitor of DNA methyltransferase-1 (DNMT1).

Methods

Ovalbumin was used as the specific antigen to establish a mouse model of FA. Intestinal IL-35⁺ regulatory B cells (Breg cells) were isolated from FA mice, and characterized using immunological approaches.

Results

FA mice had a lower frequency of IL-35⁺ Breg cells, which was inversely correlated with their FA response. The quantity of IL-35 was lower in intestinal Breg cells from FA mice. Hypermethylation status was detected in the Il35 promoter, which was accompanied with high levels of H3K9me3. Enforced expression of DNMT1 hindered the promoter activity of the IL35 gene. Administration of an inhibitor of DNMT1 (RG108) restored the immune regulatory capacity of FA intestinal Bregs, and effectively suppressed the expression of DNMT1, and attenuated experimental FA.

Conclusions

The elevated quantity of DNMT1 in intestinal Breg cells compromises the expression of IL-35 and affects the immune regulatory functions, which facilitates the development of FA. The immune regulatory functions of intestinal Breg cells are restored and experimental FA is attenuated by inhibiting DNMT1.

Aging is a gradual, inevitable physiologic process. The organ aging is related to the persistence of chronic inflammation, but the understanding of inflammatory state during renal aging is lacking currently. Single-cell transcriptome sequencing was performed on aging mouse kidney to reveal the molecular phenotype and composition changes of different cell types. In the early stage of aging, immune cells such as T, B cells and mononuclear macrophages increased in kidney. The molecular state of T cells in aging kidney changed and polarized. Among them, we identified a group of GZMK⁺ CD8 ⁺ T cells with high expression of Eomes, Pdcd1 and Ifng and a group of Il17a⁺ T cells with high expression of Il17a and Il23r. Moreover, the cytokines and inflammations can aggravate tissue damage eventually. Furthermore, we found the interaction between different types of epithelial cells and T cells increased during the renal aging. These results identify the changes of T cells in the early stage of aging kidney and suggest that GZMK⁺CD8⁺ T cells might be a potential target to ameliorate age-associated dysfunctions of kidney(Graphical Abstract).

Introduction

Shigellosis is a gastrointestinal disease causes high morbidity and mortality worldwide, however, there is no anti-Shigella vaccine. The use of antibiotics in shigellosis treatment exacerbates antibiotic resistance. Antibodies, particularly egg yolk antibody (IgY), offer a promising approach to address this challenge. This study aimed to investigate the prophylactic effect of IgY produced against a recombinant chimeric protein containing the immunogens IpaD, IpaB, StxB, and VirG from Shigella.

Methods

The chimeric protein, comprising IpaD, IpaB, StxB, and VirG, was expressed in E. coli BL21 and purified using the Ni-NTA column. Following immunization of chickens, IgY was extracted from egg yolk using the PEG-6000 method and analyzed through SDS-PAGE and ELISA techniques. Subsequently, the prophylactic efficacy of IgY was assessed by challenging of mice with 10 LD50 of S. dysenteriae and administering different concentrations of IgY (1.25, 2.5, 5, and 10 mg/kg) under various time conditions.

Results

The recombinant protein, weighing 82 kDa, was purified and confirmed by western blotting. The IgY concentration was determined as 9.5 mg/ml of egg yolk and the purity of the extracted IgY was over 90 %. The results of the ELISA showed that at least 19 ng of pure antibody identified recombinant protein and reacts with it. The challenge test employing IgY and Shigella demonstrated a direct correlation between the survival rate and antibody concentration, with increased concentrations leading to decreased mortality rates. Treatment of mice with 10 mg/kg IgY leads to 80 % survival of the mice against 10 LD50 S. dysenteriae.

Conclusion

Our findings suggest that IgY may offer therapeutic potential in treating Shigella infections and combating antibiotic resistance.

HIV-1 chronically infects host CD4⁺ T lymphocytes and further affects a variety of immune cells, including CD8⁺ T cells. In our previous study, by analyzing unbiased high-dimensional single-cell RNA-seq data (scRNA-seq), we found that the frequency of GZMK⁺CD8⁺ T cells expressing granzyme K (GZMK) was increased in people living with HIV-1 (PLWHs). However, the phenotypic and functional characteristics of these cells in chronic HIV-1 infection and their correlation with disease are not well understood. In this study, we conducted a comprehensive analysis of scRNA-seq and matched T-cell receptor repertoire (TCR) sequencing data to delve into the characterizations of GZMK⁺CD8⁺ T cells, which was further validated by flow cytometry. We observed heterogeneity within the GZMK⁺CD8⁺ T cells, which could be further subdivided into a GZMK⁺GZMB^- subset and a GZMK⁺GZMB⁺ subset, with the latter being significantly enriched in PLWHs. The GZMK⁺GZMB⁺ cells are a unique subset within CD8⁺ T cells, characterized by high proliferation, activation, inflammatory response, clone transition, etc., and are one of the differentiation endpoints by pseudotemporal analysis of CD8+αβ T cells. Despite being predominantly composed of effector memory T cells (Tem), similar to the GZMK⁺GZMB^- subset, the GZMK⁺GZMB⁺ subset exhibits differentiation at a later stage than the GZMK⁺GZMB^- subset. We also observed that the frequency/count of GZMK⁺GZMB⁺CD8⁺ T cells was negatively correlated with CD4/CD8 ratio, and positively correlated with HIV DNA, IP-10, and MIG levels in PLWHs. In vitro experiments demonstrate that GZMK can potentiate the stimulatory effects of lipopolysaccharide (LPS) on THP-1 macrophages via the TLR-4 pathway, significantly enhancing the secretion of IP-10, MIG, and MCP-1, as well as increasing the proportion of TNF-α⁺ cells. In conclusion, in PLWHs, GZMK⁺GZMB⁺CD8⁺ T cells are a highly reactive and inflammatory-inducing subset that may be associated with systemic inflammation.

Purpose

The etiology of asthma remains elusive, with no known cure. Based on accumulating evidence, autophagy, a self-degradation process that maintains cellular metabolism and homeostasis, participates in the development of asthma. Mycobacterium vaccae vaccine (M. vaccae), an immunomodulatory agent, has previously been shown to effectively alleviate airway inflammation and airway remodeling. However, its therapeutic effect on asthma via the regulation of autophagy remains unknown. Therefore, this study aimed to investigate the impact of M. vaccae in attenuating asthma airway inflammation via autophagy-mediated pathways.

Methods

Balb/c mice were used to generate an ovalbumin (OVA)-immunized allergic airway model and were subsequently administered either M. vaccae or M. vaccae + rapamycin (an autophagy activator) prior to each challenge. Next, airway inflammation, mucus secretion, and airway remodeling in mouse lung tissue were assessed via histological analyses. Lastly, the expression level of autophagy proteins LC3B, Beclin1, p62, and autolysosome was determined both in vivo and in vitro, along with the expression level of p-PI3K, PI3K, p-Akt, and Akt in mouse lung tissue.

Results

The findings indicated that aerosol inhalation of M. vaccae in an asthma mouse model has the potential to decrease eosinophil counts, alleviate airway inflammation, mucus secretion, and airway remodeling through the inhibition of autophagy. Likewise, M. vaccae could reduce the levels of OVA-specific lgE, IL-5, IL-13, and TNF-α in asthma mouse models by inhibiting autophagy. Furthermore, this study revealed that M. vaccae also suppressed autophagy in IL-13-stimulated BEAS-2B cells. Moreover, M. vaccae may activate the PI3K/Akt signaling pathway in the lung tissue of asthmatic mice.

Conclusion

In summary, the present study suggests that M. vaccae may contribute to alleviating airway inflammation and remodeling in allergic asthma by potentially modulating autophagy and the PI3K/Akt signaling pathway. These discoveries offer a promising avenue for the development of therapeutic interventions targeting allergic airway inflammation.