Effect Of Arginine On Immune Function Of Piglets After Lipopolysaccharide And Cyclophosphamide Challenge

Two experiments were conducted to investigate the effect of L-arginine (Arg) supplementation on immune function of piglets.Experiment 1 was conducted to investigate the effects of Arg on intestinal mucosal immune barrier of piglets after lipopolysaccharide (LPS) challenge. A total of eighteen piglets were randomly into one of three treatments, including:①control (CONTR);②LPS-challenged group (LPS); and③LPS+0.5% arginine (0.5% Arg). On day 16 of the trial, piglets in the LPS and 0.5% Arg groups were injected intraperitoneally with LPS at 100μg/kg body weight (BW), whereas piglets in the CONTR group were injected with an equivalent amount of sterile saline. At 48 h after injection, the piglets were slaughtered to collect intestinal samples for analysis. The results showed that: (1) LPS increased the apoptosis of lymphocyte (P<0.05) in the ileal peyer's patches. 0.5% Arg alleviated the increase of lymphocyte apoptosis (P<0.05) in the ileal peyer's patches induced by LPS. (2) LPS reduced the number of IgA secreting cells in ileum (P<0.05). 0.5% Arg alleviated the decrease of IgA secreting cells number in ileum (P>0.05). (3) LPS increased mast cells number in duodenum and ileum (P<0.05). 0.5% Arg alleviated the increase of mast cells number in duodenum and ileum (P<0.05). (4) LPS increased IL-6 and TNF-αmRNA abundance in jejunum (P<0.05), and TNF-αmRNA abundance in ileum (P<0.05). 0.5% Arg alleviated the increase of TNF-αmRNA abundance in jejunum and ileum (P<0.05). These results indicate that Arg supplementation has beneficial effects in alleviating the damage of intestinal mucosal immune barrier iuduced by LPS challenge.Experiment 2 was conducted to investigate the effects of Arg on performance and immune function of piglets after cyclophosphamide (CY) challenge. A total of twenty-four piglets were allotted randomly into one of three treatments, including: 1) control (CONTR); 2) CY-challenged group (CY); and 3) CY+0.5% Arg (0.5% Arg). On days 14 and 21 of the trial, piglets in the CY and 0.5% Arg groups were injected intraperitoneally with CY at 50 mg/kg BW, whereas piglets in the CONTR group were injected with an equivalent amount of sterile saline. Blood samples were obtained on days 21 and 28 of the trial for further analysis. On day 28, delayed-type hypersensitivity reaction was evaluated. The results showed that: (1) CY reduced average daily gain (ADG) and average daily feed intake (P<0.05), and increased feed/gain (P<0.05) from days 21 to 28. 0.5% Arg alleviated the decrease of ADG induced by CY from days 21 to 28 (P<0.05). (2) CY decreased the numbers of total white blood cells, lymphocytes, monocytes and neutrophils on day 28 (P<0.05). 0.5% Arg mitigated the decrease of total white blood cell numbers induced by CY on day 28 and improved the lymphocyte percentage on day 21 (P<0.05). (3) CY had no effect on lymphocyte proliferation and skinfold thickness indicative of delayed-type hypersensitivity reaction. 0.5% Arg increased the delayed-type hypersensitivity reaction (P<0.05). (4) CY decreased the level of the bovine serum albumin (BSA) antibody on day 28. 0.5% Arg attenuated the decrease of BSA antibody level induced by CY on day 28 (P<0.05). (5) CY decreased the serum level of interferon-γ(IFN-γ) on day 21 (P<0.05). 0.5% Arg mitigated the decrease of serum IFN-γlevel on day 21 and elevated the levels of serum interleukin-2 and IFN-γon day 28 (P<0.05). These results indicate that Arg supplementation has beneficial effects in attenuating the immunosuppressive effects of CY challenge.In a conclusion, Arg supplementation alleviated the damage of intestinal mucosal immune barrier induced by LPS challenge and the immunosuppression iuduced by CY challenge.