Bovine ADAM9 Variant Linked to Immune Response Differences

The study, published in BMC Veterinary Research, focuses on the ADAM9 N267H missense variant, a change that replaces the amino acid asparagine with histidine at position 267. This variant, designated rs210368040, involves an A to C nucleotide substitution in the coding sequence. The team confirmed the presence of this variant through Sanger sequencing of cDNA amplicons derived from bovine polymorphonuclear leukocytes, which also served to verify that ADAM9 is actively expressed in these immune cells.

ADAM9, or A disintegrin and metalloproteinase 9, is a transmembrane metalloproteinase known to play a role in leukocyte activation. However, its functional genetic variation in cattle had remained poorly characterized until this study. The researchers noted that understanding polymorphisms that alter the structure of ADAM9 is crucial for comprehending individual differences in bovine innate immune function. In silico analysis localized residue 267 to a surface-exposed loop within the metalloproteinase domain, specifically the peptidase M12B domain. This positioning suggests that the mutation introduces an amino acid with different chemical properties, which could potentially destabilize the protein domain or lead to a loss of function.

To assess the prevalence of this variant, the team genotyped 450 Polish Holstein-Friesian cows. The results revealed a genotype distribution of 234 cows with the AA genotype, 191 with the AC genotype, and 25 with the CC genotype. Following this population-level analysis, the researchers conducted ex vivo phenotyping on a smaller cohort of 27 cows, comprising 8 AA, 9 AC, and 10 CC individuals. These neutrophils were stimulated with two different bacterial ligands: Escherichia coli lipopolysaccharide (LPS) at concentrations ranging from 12.5 to 50 µg/mL, and Staphylococcus aureus peptidoglycan (PGN) at concentrations from 10 to 60 µg/mL. Statistical analysis applied within-family false discovery rate (FDR) correction to ensure the robustness of the findings, with a significance threshold of q < 0.05.

The study revealed distinct stimulus-dependent differences in immune reactivity among the genotypes. Under LPS stimulation, AA homozygotes exhibited a dose-dependent reduction in reactive oxygen species (ROS) production, which was assessed using nitroblue tetrazolium (NBT) reduction. Conversely, these same AA cows showed higher levels of extracellular double-stranded DNA release under the same LPS conditions. The findings indicate that the ADAM9 variant influences the balance between ROS production and NET-associated DNA release in a manner that depends on the specific bacterial component encountered.

In contrast, when stimulated with PGN, the CC genotype demonstrated superior NET formation compared to the other groups. This suggests that the functional impact of the ADAM9 N267H variant is not uniform across all types of immune challenges. The researchers also investigated gene expression changes using reverse transcription quantitative PCR. They found lower expression of the genes TLR2 and IRF3 in CC neutrophils under selected LPS conditions.

The study underscores the importance of ADAM9 in modulating the innate immune response in cattle. The N267H polymorphism appears to be a candidate functional variant linked to ligand-dependent innate immune responses. By altering the structure of the ADAM9 protein, this variant may influence how neutrophils process signals from different pathogens.

Overall, this research provides a detailed characterization of a functional genetic variant in a key immune gene. It highlights the intricate relationship between genetic variation and immune function in livestock.

Subject of Research: Genetic variation in bovine ADAM9 and its impact on innate immune responses

Article Title: Impact of the ADAM9 N267H missense variant on ligand-dependent NET-associated DNA release and reactive oxygen species production in bovine neutrophils

Article References: Sadowska, J., Tobolski, D., Polak, Z., Krupa, M., Pascottini, O. B., Wójcik, R., & Brym, P. (2026). Impact of the ADAM9 N267H missense variant on ligand-dependent NET-associated DNA release and reactive oxygen species production in bovine neutrophils. BMC Veterinary Research. https://doi.org/10.1186/s12917-026-06071-w

Image Credits: AI Generated

DOI: 10.1186/s12917-026-06071-w

Keywords: ADAM9, Bovine Immunology, Neutrophils, Genetic Variation, NET Formation, Reactive Oxygen Species, BMC Veterinary Research, Innate Immunity, Polish Holstein-Friesian, LPS, PGN, Impact