Arginine and Adhesion Molecules - Adhesion Molecules - page 105

functions. Previous reports revealed that supplemental dietary Arg accelerated
wound healing and improved nitrogen retention at er trauma. Arg supplementation
also increased peripheral lymphocyte mitogenesis in response to mitogens in
healthy humans and in postoperative patients (Daly et al. 1988, Barbul et al.
1990). Previous work in our laboratory demonstrated that Arg supplementation
attenuates oxidative stress, and a better in vitro macrophage response was observed
in burned mice (Tsai et al. 2002). Also, enteral Arg supplementation before sepsis
signii cantly enhances peritoneal macrophage phagocytic activity and intestinal
immunoglobin A secretion in septic rats (Wang et al. 2003, Shang et al. 2004). Arg
is considered to be an essential amino acid for patients with catabolic conditions.
Currently, Arg is added to enteral formulas at pharmacological levels in an attempt
to boost immune function and improve clinical outcomes of critically ill patients.
However, the ef ects of Arg on various immune parameters are not consistent.
Some studies showed no change (Torre et al. 1993) or a decrease (Gonce et al.
1990) in the thymus weight, splenocyte proliferation, or survival in animal studies.
Nieves and Langkamp-Henken (2002) summarized previous clinical trials that
examined the ef ect of Arg as a single variable on immune functions. h ey found
that among six double-blind, randomized controlled studies, two of the trials
showed an increase, while the other four trials showed no ef ect or a decrease
in mitogen-induced lymphocyte proliferation. No studies have demonstrated
improved outcomes with Arg supplementation. A meta-analysis included 22
randomized trials with a total of 2,419 surgical or critically ill patients to examine
the relationship of enteral nutritional supplementation using immune-enhancing
nutrients with infectious complication and mortality rates of patients. h ey found
that compared with standard enteral nutrition, an Arg-containing formula had
no ef ect on infectious complications and may increase mortality in critically ill
patients (Heyland et al. 2001). h e ei cacy of Arg supplementation on critically ill
patients remains controversial.
ARGININE AND ADHESION MOLECULES
Adhesion molecules play key roles in cell-cell interactions and cell-extracellular
matrix interactions. h ese proteins are important mediators of host defense and
are localized in the earliest inl ammatory lesions. Overexpression of adhesion
molecules by endothelial cells (ECs) and leukocytes may contribute to tissue
injury and multiple organ dysfunction. Arg modulates the inl ammatory response
perhaps partly through regulating adhesion molecules.
Atherogenesis
Hypercholesterolemia is a risk factor for atherosclerosis, and monocyte adhesion
to ECs is a key early event in atherogenesis. h e earliest observable abnormality