Fig. 1

The Impact of Tetanus Toxoid + CpG Immunization on the Heart in Space. (a) Two groups of mice were sent to the ISS for 34–35 days. One group was vaccinated with tetanus toxoid plus CpG 13 days before launch, and again after 21 days in space. A second group, vaccinated with saline only, served as a control (created with BioRender.com). Transcriptomic analysis was conducted with n = 3 biological replicates per group. (b) The volcano plot identified significant differences in the flight-immunized mice in reference to the flight control. The red clusters show a positive change, and the blue clusters show a negative change in transcript expression compared to spaceflight controls. (c) GO Enrichment analysis of statistically significant transcripts (p < 0.05) shows the enriched processes in flight-immunized mice versus flight saline mice. (d) KEGG analysis revealed that the statistically significant transcripts promoted an immune response and inflammation in the heart. (e) The heatmap lists the top 80 up- and down-regulated genes in the flight-immunized mice when compared to the flight-saline mice. Many highly regulated genes in flight-immunized mice (left three panels) were focused on immune-associated markers when compared to flight control mice (right three panels), where, in the heat map, red shows upregulation and blue downregulation in Fragments Per Kilobase Million. (f) Ingenuity Pathway Analysis of all statistically significant, differentially expressed transcripts predicted increased cytokine signaling as well as recruitment and response of immune cells (orange = predicted activation, blue = predicted downregulation). (g) Gene Set Enrichment Analysis (GSEA) shows that the inflammatory response was upregulated in the flight-immunized mice when compared to flight saline (FDR q-value = 0.0)