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Many genes that respond to infection have functions outside of immunity and have been found to be under natural selection. Pathogens may therefore incidentally alter nonimmune physiology through engagement with immune system genes. This raises a logical question of how genetically promiscuous the immune system is, here defined as how heavily cross-referenced the immune system is into other physiological systems. This work examined immune gene promiscuity across physiological systems in primates by assessing the baseline (unperturbed) expression of key tissue and cell types for differences, and primate genomes for signatures of selection. These efforts revealed “immune” gene expression to be cross-referenced extensively in other physiological systems in primates. When immune and nonimmune tissues diverge in expression, the differentially expressed genes at baseline are enriched for cell biological activities not immediately identifiable as immune function based. Individual comparisons of immune and nonimmune tissues in primates revealed low divergence in gene expression between tissues, with the exception of whole blood. Immune gene promiscuity increases over evolutionary time, with hominoids exhibiting the most cross-referencing of such genes among primates. An assessment of genetic sequences also found positive selection in the coding regions of differentially expressed genes between tissues functionally associated with immunity. This suggests that, with increasing promiscuity, divergent gene expression between the immune system and other physiological systems tends to be adaptive and enriched for immune functions in hominoids.
Brinkworth, Jessica F. and Babbitt, Courtney C.
"Immune System Promiscuity in Human and Nonhuman Primate Evolution,"
4, Article 2.
Available at: https://digitalcommons.wayne.edu/humbiol/vol90/iss4/2
Final Table_S2_immune_genes_expressed_in_nonimmune_tissues.xlsx (83 kB)
Final Table_S4_I_v_NI_fdr0_1_FC20_Gorilla_Revigo.xlsx (295 kB)
Final TableS3_DE_genes.xlsx (19968 kB)
Final TableS5_I_v_NI_Pairwise contrast _enrichment.xlsx (7454 kB)
Final Table_S6_dN_dS_scores.xlsx (1109 kB)