The Upregulation of Cathepsin G Is Associated with Resistance to Bovine Paratuberculosis

Abstract

An in silico genomic–transcriptomic combined approach allowed the identification of a polymorphism (cis-eQTL-rs41976219) in the Bos taurus genome associated with the CTSG mRNA expression in bovine blood samples, which suggests that individual genetic variation might modulate the CTSG transcriptional response. In the current study, a sandwich ELISA is used to measure the CTSG protein levels in supernatants of monocyte-derived macrophages (MDMs) isolated from cows with the AA (n = 5) and AC (n = 11) genotypes for the rs41976219 and infected ex vivo with MAP. Cows with the AC genotype have significantly higher CTSG protein levels (1.85 ng/mL) in the supernatants of enriched CD14+-MDMs after 2 h of infection when compared with infected CD14+-MDMs from cows with the AA genotype (1.68 ng/mL). Statistically significant differences in the intracellular MAP load at 7 d p.i. are observed between animals with the AA (2.16 log CFUs) and AC (1.44 log CFUs) genotypes. Finally, the association between the rs41976219 allelic variants and resistance to PTB is tested in a larger cattle population (n = 943) classified according to the presence (n = 442) or absence (n = 501) of PTB-associated lesions. The presence of the two minor alleles in the rs41976219 (CC) is more frequent among healthy cows than in cows with PTB-associated lesions in gut tissues (2.2% vs. 1.4%, OR = 0.61). In agreement with this, the CTSG levels in plasma samples of cows without lesions in gut tissues and with the CC (n = 8) genotype are significantly higher than in the plasmas of cows with the AA + AC (n = 36) genotypes.

Control of Mycobacterium avium subsp. paratuberculosis load within infected bovine monocyte-derived macrophages is associated with host genetics

“…Since ex vivo assays measure the capacity of a cell population to respond to a challenge, functional testing represents the best way to evaluate resistance and vaccine protection (45). MGIA assays using bovine MDMs were previously used to assess macrophages´s capacity to clear MAP strains isolated from different hosts (23, 24), to test novel therapeutic approaches for the treatment of MAP-infected animals (46), and to test vaccines' efficacy and protection (47).…”

Summary-data based mendelian randomization identifies gene expression regulatory polymorphisms associated with bovine paratuberculosis by modulation of the nuclear factor Kappa β (NF-κß)-mediated inflammatory response

“…Connecting non-coding variants and downstream affected genes is a challenge and, up to date, only a few functional mutations or expression quantitative loci (eQTLs) with causative effects over PTB susceptibility or resistance have been characterized (Canive et 21 ). A common practice following GWAS is to map genes near the identi ed SNPs based on haplotype and linkage disequilibrium.…”

Summary-data based Mendelian randomization identifies gene expression regulatory polymorphisms associated with bovine paratuberculosis by modulation of the nuclear factor Kappa β (NF-κß)-mediated inflammatory response

“…Most of the GWAS-identified SNPs are located in non-coding regions of the genome, including intergenic and intronic regions that are enriched in regulatory elements indicating that those variants exert their effects through the modulation of gene expression [ 29 ]. Connecting non-coding variants and downstream affected genes is a challenge and, up to date, only a few functional mutations or expression quantitative loci (eQTLs) with causative effects over PTB susceptibility or resistance have been characterized [ 30 – 32 ]. A common practice following GWAS is to map genes near the identified SNPs based on haplotype and linkage disequilibrium.…”