Effect of bovine lactoferrin on T lymphocyte cell phenotype and function and the response to vaccination in the neonatal piglet
Deficiencies of the immune system, both innate and adaptive immunity, can weaken host defense and increase susceptibility to infection. The immune system exists to guard the host against pathogenic infections, particularly at stressful time periods, such as birth and weaning. Proper nutrition and vaccination have positive effects for infant immune maturation. Lactoferrin (Lf), an iron binding glycoprotein found in breastmilk has been shown to have numerous physiological and immune properties that are nutritionally advantageous for infants. The goal of this thesis research was to discover how early nutrition influences immune maturation by investigating the addition of bovine Lf (bLf) to infant formula. The overall hypothesis of this research was that immune development is disparate between formula-fed and sow-reared piglets and that addition of bLf would enhance vaccination response and T-cell function in formula-fed piglets. To address this hypothesis, two specific aims were undertaken. N Specific Aim 1 investigated the effect of bLf supplemented to infant formula on the response to immunization against influenza virus and serum Ig profiles compared to piglets that were sow-reared or fed unsupplemented formula. Newborn piglets were obtained at 4h of age and were fed either medicated sow milk replacer (FF; n=22) or sow milk replacer formula with 1g/L bovine lactoferrin (bLf) (LF; n=22). A reference control group remained with the sow (SR; n=25). Half of the piglets were further randomized into two groups to receive an IM injection of Fluzone™ on d7 and d14. On d21 postpartum, piglets in each group were euthanized and blood and secondary lymphoid tissue samples were collected. Intestinal weight and length was collected immediately following euthanasia and serum was collected for analysis of Fluzone™-IgG and total IgG and IgM concentrations. Formula intake between FF and LF piglets did not differ. However, the body weight of the piglets was influenced by diet early in the study. Sow-reared piglets weighed more than both FF groups at day 3 and for the duration of the study (p<0.0001). LF piglet intake was approximately 0.38g/kg BW of Lf for the duration of the study. Also, at day 21 LF piglets weighed more than FF piglets (p<0.0001). When intestinal length was normalized by body weight (cm/kg), SR piglets had less normalized intestinal length in comparison to FF and LF. Similarly intestinal weights (g), which were normalized by body weight (g/kg) and intestinal length (g/cm), were significantly lower in SR piglets in comparison to FF and LF piglets (p<0.0001). A trend was observed in antibody response in dietary treatments, where SR piglets had greater Fluzone™-IgG versus the FF and LF groups (p=0.0953). However, LF had no impact on total IgG and IgM profiles. Specific Aim 2 examined the effect of bLf supplemented to infant formula on T-lymphocyte phenotypes and cytokine secretion following ex vivo stimulation. T-lymphocyte populations in peripheral blood mononuclear cells (PBMC), mesenteric lymph nodes (MLN) and spleen were stained with specific antibodies and identified by using flow cytometry. T-cell and cytokine responses to ex vivo stimulation were assessed by ELISA. Both dietary (SR vs. LF vs. FF) and vaccination effects on immunological development were observed. Few differences in T-cell subpopulations were observed in PBMC, MLN and spleen. Yet, when vaccination was removed from the model, memory T-cells from PBMC were greater in FF piglets than LF piglets, but not different between SR piglets (p=0.0388). After ex vivo stimulation, numerous diet and vaccination effects were identified. First, changes in PBMC T-cells were observed after culturing. FF piglets had higher amounts of CD8+ T-cells than LF or SR (p<0.0001). In contrast, SR piglets had higher T-helper cells (CD4+) than LF and FF piglets (p<0.0001). Also, LF piglets had decreased memory (CD4+CD8+) T-cells when compared to FF or SR piglets after stimulation (p=0.0400). In the spleen, SR piglets had greater CD8+ T-cells than LF or FF piglets (p=0.0054). Yet, FF piglets had greater CD4+ T-cells than SR piglets, while LF was an intermediate (p=0.0006). Again, diet differences were observed in the spleen, where SR piglets had higher amounts of CD4+CD8+ T-cells than LF or FF piglets (p=0.0004). In MLN, vaccinated piglets had greater CD8+ T-cells when stimulated than non-vaccinated piglets (p=0.0293). Yet in MLN supernatants, dietary differences were observed in FF piglets who secreted more IL-12 than LF or SR piglets from cells that were unstimulated or stimulated with PHA and PMA (p=0.0041). When vaccination was removed, spleen IL-12 cytokine production following Fluzone™ stimulation was affected by diet. LF piglets had higher IL-12 secretion than SR piglets, while FF was an intermediate (p=0.0394). Overall, vaccination and serum Ig profiles in the neonatal piglets were minimally affected by dietary supplementation of 1.0 g/L bLf. Dietary bLf was found to have little impact on T-cell phenotype or cell-mediated immune responses. More specifically, bLf decreased the percentage of memory T-cells in PBMC in comparison to SR and FF piglets. Dietary bLf was also found to have no negative impacts on development, dietary tolerance or immune characteristics analyzed. However, this data demonstrates differences that exist between SR piglets in comparison to FF and LF piglets and provide a framework for future dietary supplementation studies.
Immune System, Breastfeeding, Lactoferrin, Neonatal, Piglet
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign