Dietary l-glutamine supplementation improves pregnancy outcome in mice infected with type-2 porcine circovirus

Abstract

Porcine circovirus type 2 (PCV2) causes reproductive failure in swine. As glutamine can enhance immune function in animals, this study was conducted with mice to test the hypothesis that dietary glutamine supplementation will improve pregnancy outcome in PCV2-infected dams. Beginning on day 0 of gestation, mice were fed a standard diet supplemented with 1.0% L-glutamine or 1.22% L-alanine (isonitrogenous control). All mice were infected with PCV2 (2000 TCID50) on day 10 of gestation. On day 17 of gestation, six mice from each group were euthanized to obtain maternal tissues and fetuses for hematology and histopathology tests. The remaining mice continued to receive their respective diets supplemented with 1.0% L-glutamine or 1.22% L-alanine through lactation. The PCV2 virus was present in maternal samples (serum and lung) of most mice in the control group but was not detected in the glutamine-supplemented mice. Dietary glutamine supplementation reduced abortion, decreased fetal deaths, and enhanced neonatal survival. The glutamine treatment also reduced concentrations of interleukin-6, while increasing concentrations of tumor necrosis factor-α and C-reactive protein, in the maternal serum of mice. Furthermore, glutamine supplementation attenuated microscopic lesions in maternal tissues (lung, spleen, and liver). Collectively, these results indicate that dietary glutamine supplementation is beneficial for ameliorating reproductive failure in virus-infected mice. The findings support the notion that gestating dams require adequate amounts of dietary glutamine for the optimal survival and growth of embryos, fetuses, and neonates, and have important implications for nutritional support of mammals (including swine and humans) during gestation and lactation.

Effects of dietary l-glutamine supplementation on specific and general defense responses in mice immunized with inactivated Pasteurella multocida vaccine

“…Primers were designed with Primer 5.0 according to the mouse gene sequence or synthesized according to the previous reports. Primers were reported in a previous study (Ren et al 2013e) or are shown in Table 1. Beta-actin was used as an internal control to normalize target gene transcript levels.…”

“…The number of viable bacteria in the heart, liver, spleen, lung and kidney was measured by homogenizing tissues in saline, plating serial dilutions on the Martin broth agar, and counting CFU after 16 h of growth at 37°C (Ren et al 2013e). …”

“…We have reported that arginine or proline boosts antibody production in vaccine-immunized mice (Ren et al 2013i, b). These findings indicate that glutamine may affect specific immune responses, such as clearance of pathogens and the expression of major virulence factors in vivo (Ren et al 2013e). Thus, it is possible that glutamine plays an important role in regulating antibody production in vaccineimmunized hosts.…”

“…This amino acid is also capable of regulating gene expression and cell signaling pathways in various cell types, including immunocytes (Li et al 2007). Results of recent compelling studies have indicated that glutamine regulates the general defense responses, including the production of cytokines (Ren et al 2013e), the function of immune cells Lai et al 2004), and the expression of innate immune regulators, e.g., like toll-like receptors (Ren et al 2013e) in various animal models. However, little is known about effects of dietary glutamine on general or specific defense responses in an animal model immunized with a vaccine.…”

Functional amino acids in nutrition and health

“…Some of the nutritionally ''nonessential'' AA (e.g., arginine, glutamine, glutamate, glycine, and proline for adults) play important roles in regulating gene expression (Kim et al 2011a, b;Wu et al 2011a, b) and micro-RNA levels (Liu et al 2012), cell signaling Jewell et al 2013), blood flow , nutrient transport and metabolism in animal cells (Suryawan et al 2012;Wang et al 2013), development of brown adipose tissue , intestinal microbial growth and metabolism (Dai et al 2012a, b), anti-oxidative responses (Hou et al 2012a, b), as well as innate and cell-mediated immune responses (Ren et al 2011(Ren et al , 2013. Of particular interest, AA participate in and modulate cell signaling through: (1) several well-conserved protein kinases (including mammalian target of rapamycin, AMP-activated protein kinase, cGMP-dependent kinase, cAMP-dependent kinase, and mitogen-activated protein kinase), (2) G protein-coupled receptors, and (3) gaseous molecules, including NO, CO, and H 2 S (Wu 2013).…”