Metabolic Reprogramming of Immune Cells Following Vaccination: From Metabolites to Personalized Vaccinology

Identifying metabolic signatures induced by the immune response to vaccines allows one to discriminate vaccinated from non-vaccinated subjects and decipher the molecular mechanisms associated with the host immune response. This review illustrates and discusses the results of metabolomics-based studies on the innate and adaptive immune response to vaccines, long-term functional reprogramming (immune memory), and adverse reactions. Glycolysis is not overexpressed by vaccines, suggesting that the immune cell response to vaccinations does not require rapid energy availability as necessary during an infection. Vaccines strongly impact lipids metabolism, including saturated or unsaturated fatty acids, inositol phosphate, and cholesterol. Cholesterol is strategic for synthesizing 25-hydroxycholesterol in activated macrophages and dendritic cells and stimulates the conversion of macrophages and T cells in M2 macrophage and Treg, respectively. In conclusion, the large-scale application of metabolomics enables the identification of candidate predictive biomarkers of vaccine efficacy/tolerability.

Blood-based microRNAs as Potential Diagnostic biomarkers for Melanoma: A Meta-analysis

INTRODUCTION

Circulating microRNAs (miRNAs) serve as noninvasive diagnostic markers in many cancers. This meta-analysis aims to evaluate the diagnostic efficacy of circulating microRNAs for melanoma.

MATERIAL AND METHODS

The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and ROC curve were evaluated using the Meta-Disc V.1.4 and Comprehensive Meta-Analysis V.3.3 software packages. To investigate the heterogeneity, the I2 and Chi-square tests were used. The publishing bias was evaluated using Begg's rank correlation and Egger regression asymmetry tests.

RESULTS

A total of 9 articles covering 13 studies (more than 50 miRs individually and in combination) were included, containing 1,355 participants (878 cases and 477 controls). The overall pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR), and AUC were 0.78 (95% CI: 0.76-0.81), 0.80 (95% CI: 0.77-0.83), 4.32 (95% CI: 3.21-5.82), 0.17 (95% CI: 0.09-0.32), 28.0 (95% CI: 15.34-51.09), and 0.91, respectively. According to Begg's and Egger's tests, there was no publication bias (Begg's p = 0.160 and Egger's p = 0.289).

CONCLUSION

Circulating miRNAs can serve as fair and non-invasive diagnostic biomarkers for melanoma. Additionally, specific miRNAs still need to be discovered for diagnosing melanoma.

Distinct Antigen Delivery Systems Induce Dendritic Cells' Divergent Transcriptional Response: New Insights from a Comparative and Reproducible Computational Analysis

Vaccination is the most successful and cost-effective method to prevent infectious diseases. However, many vaccine antigens have poor in vivo immunogenic potential and need adjuvants to enhance immune response. The application of systems biology to immunity and vaccinology has yielded crucial insights about how vaccines and adjuvants work. We have previously characterized two safe and powerful delivery systems derived from non-pathogenic prokaryotic organisms: E2 and fd filamentous bacteriophage systems. They elicit an in vivo immune response inducing CD8+ T-cell responses, even in absence of adjuvants or stimuli for dendritic cells’ maturation. Nonetheless, a systematic and comparative analysis of the complex gene expression network underlying such activation is missing. Therefore, we compared the transcriptomes of ex vivo isolated bone marrow-derived dendritic cells exposed to these antigen delivery systems. Significant differences emerged, especially for genes involved in innate immunity, co-stimulation, and cytokine production. Results indicate that E2 drives polarization toward the Th2 phenotype, mainly mediated by Irf4, Ccl17, and Ccr4 over-expression. Conversely, fd-scαDEC-205 triggers Th1 T cells’ polarization through the induction of Il12b, Il12rb, Il6, and other molecules involved in its signal transduction. The data analysis was performed using RNASeqGUI, hence, addressing the increasing need of transparency and reproducibility of computational analysis.