|Myers, Michael - US FDA|
|Farrell, Dorothy - US FDA|
|Cope, Carol - US FDA|
|Henderson, Mark - US FDA|
Submitted to: Immunological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 18, 1995
Publication Date: N/A
Interpretive Summary: Research by others has suggested that recombinant porcine somatotropin (rPST) could potentially alter immune responses in swine, especially following microbial infection. Accordingly we determined the effect of either rPST or chromium picolinate (CrP) administration on the in vivo production of TNF-alpha and interlukin-6 (IL-6) following endotoxin challenge (to mimic bacterial septicemia) and the ex vivo production of IL-2 and IL-6 from peripheral blood mononuclear cells. Cytokines, such as TNF-alpha, IL-2, and IL-6 can serve as biomarkers, or indirect measures, of the status of the immune system. In this study, we observed no significant effect on production of either IL-2 or IL-6 by mononuclear cells obtained from swine treated with rPST. Likewise, there were no differences in the amount of IL-6 produced by rPST treated swine following endotoxin challenge as compared to controls. In contrast, mononuclear cells obtained from CrP supplemented swine had elevated levels of IL-2. There were no differences in IL-6 production. Following endotoxin challenge, CrP supplemented swine demonstrated almost a 4-fold increase in plasma IL-6 levels as compared to controls. The results of this study suggest that long term use of CrP will augment production of IL-2 and IL-6, whereas rPST will not. While the results of the present study demonstrated no effect of long-term rPST on cytokine production, one cannot infer that rPST does not affect other aspects of the immune system in swine.
Technical Abstract: The effect of dietary chromium picolinate (CrP) and recombinant porcine growth hormone (rPST) administration on growth performance and cytokine production in crossbred gilts was determined using a 2 x 2 treatment array. Treatments were: control (basal diet), CrP supplemented diet (basal + 300 ug Cr+3 as CrP/kg diet), rPST (100 ug/kg body weight/day), and rPST + CrP. CrP supplemented diets were fed beginning at 20 kg body weight through 90 kg. Administration of rPST was begun at 60 kg body weight and continued through 90 kg. All rPST treated pigs demonstrated improvements in growth performance versus controls. Pigs given CrP supplemented diets showed no differences in growth performance. At 90 kg, pigs were challenged with endotoxin (lipopolysaccharide [LPS], 0.2 ug/kg; iv). Blood samples were collected at 0, 1, and 3 hours post-challenge. Plasma IL-6 levels increased from 23 U/ml at time 0 to 1927 U/ml at 3 hours for control swine. Swine from the CrP treatment group had IL-6 levels of 8130 U/ml at 3 hours post-LPS. There were no differences in plasma IL-6 from pigs in the rPST and rPST + CrP treatment groups compared to the controls. Endotoxin challenge had no effect on either blood glucose levels or induction of TNF-alpha in any treatment group. Peripheral blood mononuclear cells from CrP treated pigs produced more IL-2 than those from all other groups.