Utilization of the Porcine System to Study Lymphotoxin-β Regulation in Intestinal Lymphoid Tissue

Reverse transcription real-time PCR for detection of porcine interferon α and β genes

A few studies provided convincing evidence of constitutive expression of type I interferons (IFNs) in humans and mice, and of the steady-state role of these cytokines under health conditions. These results were later confirmed in pigs, too. In line with this tenet, low levels of IFN-α/β can be detected in swine tissues in the absence of any specific inducer. These studies are compounded by the utmost complexity of type I IFNs (including among others 17 IFN-α genes in pigs), which demands proper research tools. This prompted us to analyse the available protocols and to develop a relevant, robust, reverse transcription (RT) real-time polymerase chain reaction (PCR) detection system for the amplification of porcine IFN-α/β genes. The adopted test procedure is user-friendly and provides the complete panel of gene expression of one subject in a microtitre plate. Also, a proper use of PCR fluorochromes (SYBR(®) versus EvaGreen(®) supermix) enables users to adopt proper test protocols in case of low-expression porcine IFN-α genes. This is accounted for by the much higher sensitivity of the test protocol with EvaGreen(®) supermix. Interestingly, IFN-β showed the highest frequency of constitutive expression, in agreement with its definition of 'immediate early' gene in both humans and mice. Results indicate that the outlined procedure can detect both constitutively expressed and virus-induced IFN-α/β genes, as well as the impact of environmental, non-infectious stressors on the previous profile of constitutive expression.

Molecular cloning, tissue expression, and subcellular localization of porcine peptidoglycan recognition proteins 3 and 4

Peptidoglycan recognition proteins (PGRPs) are innate immune molecules that are present in most invertebrates and vertebrates. Mammals have four PGRPs, PGLYRP1-4. In the present study, we cloned the cDNAs encoding porcine PGLYRP3 and 4 from the esophagus of adult swine. The length of the complete open reading frames of porcine PGLYRP3 and 4 are identical and contain 1125bp encoding 374 amino acid residues. The amino acid sequences of these two proteins were more similar to their human orthologs (78.9% [PGLYRP3] and 73.9% [PGLYRP4]) than to their mouse orthologs (71.3% [PGLYRP3] and 67.9% [PGLYRP4]). Expression analysis revealed that both PGLYRP3 and 4 were more strongly expressed in digestive tract, especially the esophagus, than in immune organs such as spleen or mesenteric lymph nodes in both newborn and adult swine. To analyze the subcellular distribution of porcine PGLYRP1-4, we constructed transfectant cell lines. Western blot and flow cytometric analyses revealed that porcine PGLYRP3 and 4 are not only secreted, but also expressed on the cell surface, unlike PGLYRP1 and 2. These results should help contribute to the understanding of PGLYRP3- and 4-mediated immune responses via their recognition of intestinal microorganisms in newborn and adult swine.