RESUMO
Susceptibility to pathogen infections and efficacy of vaccination highly depend on the immune status of the piglet. Here, we measured immunocytes in piglets from birth to weaning to elucidate how immunocyte populations change during development and are affected by weaning. Crossbred piglets were used. Suckling piglets were euthanized at 1, 7, 14, 21, 28 or 35 days old (3~4 piglets at each time point). In addition, seven piglets were weaned at 21 days old, with four being euthanized at 28 days old and the remaining at 35 days old. Piglet carcasses were dissected, and blood, mesenteric lymph nodes (MLN) and spleen were sampled. In total, seven antibodies were used to stain the immunocyte population. Dynamics of myeloid (CD3−SWC3+CD16+), natural killer (NK; CD3−SWC3−CD16+), killer T (CD3+CD8+), helper T (CD3+CD4+) and B (CD3−CD21+) cells were analyzed. Percentage of innate immunity cells such as myeloid cells declined (p < 0.05) from the first day after birth. In contrast, percentage of NK cells increased in piglets while they were still suckling. Killer T, helper T, and B cell populations increased around 2~3 weeks after birth. No significant differences in the populations of the evaluated cell types were observed between suckling and weaned piglets at least for 14 days post weaning.
RESUMO
Transcriptome analyses were conducted on the ileal mucosa of 14- to 35-day-old piglets to investigate postnatal gut development during suckling and postweaning. The transcriptome profiles of 14-day-old suckling piglets showed a considerably higher number of differentially expressed genes than did those of 21-, 28-, and 35-day olds, indicating an intensive gut development during the first 14-21 postnatal days. In addition, the analysis of biological pathways indicated that Chemotaxis Leucocyte chemotaxis was the most significantly affected pathway in suckling piglets between 14 and 21 days of age. Weaning negatively affected pathways associated with acquired immunity, but positively affected those associated with innate immunity. Interestingly, pathway Chemotaxis Leucocyte chemotaxis was found positively affected when comparing 14- and 21-day-old suckling piglets, but negatively affected in 28-day-old piglets weaned at 21 days of age, when compared with 28-day-old suckling piglets. Genes CXCL13, SLA-DOA (MHC class II), ICAM1, VAV1, and VCAM1 were involved in the pathway Chemotaxis Leukocyte chemotaxis and they were found to significantly change between 14- and 21-day-old suckling piglets and between groups of suckling and weaned piglets. The expression of these genes significantly declined after weaning at 14, 21, and 28 days of age. This decline indicated that CXCL13, SLA-DOA, ICAM1, VAV1, and VCAM1 may be involved in the development of Peyer's patches (PP) because lower gene expression clearly corresponded with smaller areas of PP in the ileal mucosa of piglets. Moreover, weaning piglets prior to a period of intensive gut development, i.e., 14 days of age, caused significant adverse effects on the size of PP, which were not reverted even 14 days postweaning.
