Analysis of porcine macrophage immune response to antigenic molecules and short chain fatty acids / 동물의과학연구지

Macrophages play an important role in both the innate and adaptive immune responses. These include phagocytosis, killing of microorganisms, antigen presentation, and induction of immune cytokines and antimicrobial genes. Macrophage activity is reported to be controlled by diverse exogenous antigenic or endogenous metabolic molecules, and the underlying mechanisms are well documented in human and mouse macrophage cells. Bacterial lipopolysaccharide (LPS) is known to be one of the most potent stimuli activating macrophages through the toll like receptor 4 (TLR4) signaling pathway. There are other antigenic molecules, such as muramyl dipeptide (MDP) and outer membrane protein A (OmpA), that are also known to activate immune cells. On the other hand, short chain fatty acids (SCFAs) such as acetate and butyrate are produced by gut microbiota and control host energy metabolism and signal transduction through GPR receptors. However, there are few studies demonstrating the effects of these molecules in macrophages from domestic animals, including domestic pigs. In this study, we attempted to characterize gene expression regulation in porcine macrophages (PoM2, Pig Monocytes clone 2) following treatment with LPS, MDP, OmpA, and two short chain fatty acids using porcine genome microarray and RT-PCR techniques. A number of novel porcine genes, including anti-microbial peptides and others, appeared to be regulated at the transcriptional level. Our study reports novel biomarkers such as SLC37A2, TMEN184C, and LEAP2 that are involved in the porcine immune response to bacterial antigen LPS and two short chain fatty acids.

Characterization of two antimicrobial peptides identified from a random peptide library and expressed in the methylotrophic yeast pichia pastoris / 동물의과학연구지

Antimicrobial peptides (AMPs) are an important component of innate defense mechanisms with broad-spectrum activities against various pathogenic microorganisms, including Gram-positive and Gram-negative bacteria, fungi, and viruses. Antibiotic resistance has become a pervasive and global health burden, resulting in the immediate need to develop a new class of antibiotic substances. We screened a 16-mer random peptide library using the yeast two-hybrid system with Beclin 1 as bait and found that two 16-mer peptides (named P4 and P30) appeared to interact with Beclin1 in the beta-gal assay. The two candidate cDNAs were introduced into the yeast secretory system of Pichia pastoris and their expression induced in the presence of methanol. Spectrophotometric analysis and Disc clear zone assay using the supernatant of the yeast growth media showed that both of the two peptides had strong activities against Staphylococcus aureus, MRSA (methicillin resistance Staphylococcus aureus), MRSA2242, and MRSA-2250, but no effect on commensal Lactobacillus strains. PCR analysis of the genomic DNA of transformed Pichia pastoris using AOX1 primers revealed that the two cDNAs were integrated into the genome at the AOX1 locus. Our result suggests that these peptides could be developed as a useful alternative to classic chemical antibiotics.