B lymphocyte differentiation and suppressor activity by T lymphocytes derived from neonatal and sucking piglets

Unlocking the power of short-chain fatty acids in ameliorating intestinal mucosal immunity: a new porcine nutritional approach

Short-chain fatty acids (SCFAs), a subset of organic fatty acids with carbon chains ranging from one to six atoms in length, encompass acetate, propionate, and butyrate. These compounds are the endproducts of dietary fiber fermentation, primarily catalyzed by the glycolysis and pentose phosphate pathways within the gut microbiota. SCFAs act as pivotal energy substrates and signaling molecules in the realm of animal nutrition, exerting a profound influence on the intestinal, immune system, and intestinal barrier functions. Specifically, they contibute to 60-70% of the total energy requirements in ruminants and 10-25% in monogastric animals. SCFAs have demonstrated the capability to effectively modulate intestinal pH, optimize the absorption of mineral elements, and impede pathogen invasion. Moreover, they enhance the expression of proteins associated with intestinal tight junctions and stimulate mucus production, thereby refining intestinal tissue morphology and preserving the integrity of the intestinal structure. Notably, SCFAs also exert anti-inflammatory properties, mitigating inflammation within the intestinal epithelium and strengthening the intestinal barrier's defensive capabilities. The present review endeavors to synthesize recent findings regarding the role of SCFAs as crucial signaling intermediaries between the metabolic activities of gut microbiota and the status of porcine cells. It also provides a comprehensive overview of the current literature on SCFAs' impact on immune responses within the porcine intestinal mucosa.

Early identification of neonates at risk: traits of newborn piglets with respect to survival

Despite technological changes and improved management, piglet mortality remains a problem for both production and welfare. Most preweaning mortality occurs within the first 3 days after birth because of problems with adaptation and development. Thus, the purpose of our study was to determine the physiologic state of newborn pigs with respect to piglet survival. Data were collected from 1024 live-born piglets of 106 primiparous German Landrace sows to analyze relationships between farrowing traits, early postnatal vitality and blood chemistry, including immunity of piglets at birth. Surviving piglets were compared with those that died during the first 10 days of life. The survivors were significantly heavier at birth (P=0.001), were born earlier in the birth order (P=0.04), reached the udder and took in first colostral milk more quickly (P=0.001) and had a smaller drop in rectal temperature I h after birth (P=0.001) than dead. However, dead piglets had significantly higher blood levels of inorganic phosphorus (P=0.0001), calcium (P=0.04) and urea (P=0.05), but a lower concentration of alpha2-macroglobulin and lower lymphocyte proliferation indices in response to pokeweed mitogen (P=0.05). Models fitted for discrimination between survivors and piglets that died included, in addition to birth weight and litter size, the foraging behavior of neonates (time from birth to first suckle) and their thermoregulatory capacity (rectal temperature 1 h after birth) in the first experimental unit, as well as prenursing biochemical measures (inorganic phosphorus, calcium and glucose) in the second experimental unit. These ethophysiological and biochemical traits of early postnatal vitality are important determinants of maturity and development at birth. Hence, breeding programs and perinatal housing and feeding conditions should ensure a high physiological maturity to improve mortality rates of neonates.

Maturation of the mitogen responsiveness, and IL2 and IL6 production by neonatal swine leukocytes

The maturation of the immune system of neonatal piglets was studied by following changes in the phenotypic composition and function of blood-borne leukocytes. The proportion of mature T and B lymphocytes decreased in the first week of birth and the circulating cells had poorly developed capacities to respond to mitogens and to secrete interleukins. From the end of the first week, however, there was a steady increase in the proportion of mature T cells (CD4+ and CD8+) and B cells in blood until 6-7 weeks after birth, when the study was ended. By 3-4 weeks, the relative proportions of different lymphocyte subsets resembled an adult-type composition. As they increased in prevalence, lymphocytes also developed capacities to proliferate and secrete interleukins. Proliferative responses to T-cell and B-cell mitogens reached adult levels within 2 weeks and 4-5 weeks, respectively. Blood leukocytes produced large quantities of IL6 by 1-2 weeks after birth and IL2 by 2-3 weeks. In contrast to lymphocyte patterns, the myeloid and granulocyte lineages were dominant at birth but then declined steadily. Unlike lymphocytes, the monocytes, macrophages and granulocytes appeared to be fully functional from the time of birth and exhibited a strong oxidative burst after appropriate stimulations. The magnitude of this response remained constant over the first 6-7 weeks. These results indicate that the first 3-4 weeks of post-natal life are a particularly susceptible interval for newborn piglets because constitutive and functional components necessary for specific cellular immune responses remain immature. This deficit may be offset by non-specific cellular mechanisms and maternally derived antibodies.

In vivo modulating effects of bacterial peptidoglycans on PHA-induced responses of porcine PBL and splenocytes

The modulating effect of Brevibacterium divaricatum cell wall derivatives, i.e. peptidoglycan monomer (PGM) and peptidoglycan polymer (PGP) on phytohemagglutinin (PHA)-induced responses of peripheral blood lymphocytes (PBL) and spleen lymphocytes (SPL) from neonatal pigs farrowed to gilts or sows was tested. Both, PBL from progeny of sows and SPL from progeny of gilts responded significantly lower (P < 0.01) when PGM (14 mg/kg) was given by intraperitoneal (IP) route at Day 0 and Day 7 after farrowing as compared to the respective controls. When the same amount of PGM was given i.p. at Day 7 and Day 14, the responses of PBL and SPL from offspring of gilts were much higher (P < 0.01) than those of nontreated controls. The treatment with PGP (2.5 mg/kg) by the same route at Day 7 and Day 14 strongly stimulated (P < 0.01) the responses of PBL and SPL of pigs originating from litters of either gilts or sows, respectively.

In vitro modulating effects of porcine immunoglobulin G on mitogens-induced lymphocyte response in precolostral, suckling and weaned piglets

The influence of allogeneic IgG on in vitro reactivity of peripheral blood lymphocytes (PBL) of neonatal colostrum-deprived piglets as well as of suckling and weaned piglets was studied. PBL were preincubated with purified allogeneic IgG for 24 h before their ability to respond to PHA, Con A or PWM was tested. PBL of precolostral piglets pretreated with allogeneic IgG exhibited higher response to PHA (P less than 0.01) than untreated control cells. An increased response of PBL treated with IgG was also observed in suckling piglets as compared to their respective control cells (P less than 0.01). Responsiveness of PBL treated with IgG to PWM was suppressed. No differences in response to Con A regardless of the sources of lymphocytes was observed as compared to IgG untreated controls. The results suggest that pretreatment of lymphocytes of piglets with allogeneic IgG modulates their reactivity to mitogens, suppressing the response to PWM and stimulating the response to PHA, respectively.