Early atherosclerotic plaques in the aorta following cytomegalovirus infection of mice

We show here that BALB/c mice inoculated with murine cytomegalovirus (MCMV) express viral antigens in the endothelial and smooth muscle cells of the aortic wall, and that accumulation of inflammatory cells in the aortic lumen, similar to that seen in early atherosclerotic lesions in humans, colocalizes with the site of virus antigen expression. Immunosuppression of the mice at the time of virus infection increased the expression of viral antigens and the size of early atherosclerotic lesions in the intima. The percentage of the low-density lipoprotein cholesterol (LDL-C), the major lipid contributor to atherosclerotic plaques, was significantly increased in the serum of MCMV-infected mice, whether or not the mice were fed a high cholesterol diet. Human cytomegalovirus (HCMV) significantly increased the esterified cholesterol component of the total cholesterol in a human arterial smooth muscle cell line infected in vitro with HCMV. These results suggest that CMV infection is involved in two of the major mechanisms that lead to development of atherosclerosis, i.e., immune injury and high LDL-C.

Fiber: effect on bacterial translocation and intestinal mucin content

Total parenteral nutrition (TPN) and elemental diet (ED) produce intestinal atrophy and increase bacterial translocation (BT) to mesenteric lymph nodes. The increased rate of BT may be due to alterations in mucosal structure, enzyme activity, or mucin content. Fiber improves intestinal structure and function in rats and may reduce the rate of BT. This study determined whether the addition of fiber to TPN or ED would maintain intestinal integrity and decrease BT to the mesenteric lymph nodes. Fifty-six adult male Sprague-Dawley rats underwent placement of jugular catheters and were assigned to one of five dietary groups: TPN, TPN+oral oat fiber (TPNF) 2 g/day, ED, ED+oral oat fiber (EDF) 2 g/day, or AIN-76 (control); they were pair-fed for 7 days. On day 8 the mesenteric lymph nodes were removed for bacterial cultures; and jejunal mucosal weight, DNA, protein, alkaline phosphatase, maltase, and jejunal mucin content were measured. Enteral nutrition significantly decreased BT when compared to parenteral feeding, and fiber significantly decreased BT when administered to rats receiving TPN or ED. Improvements in intestinal mucosal structure were not consistently associated with decreased rates of BT. Additionally, BT occurred independently of jejunal mucin concentration. Mechanisms other than maintenance of mucosal structure or mucin content are important in the mediation of fiber-induced decreased BT in rats receiving TPN or ED.

Butyrate increases colonocyte protein synthesis in ulcerative colitis

Butyrate promotes epithelial cell healing and improves symptoms when administered rectally in patients with distal ulcerative colitis (UC). It was hypothesized that butyrate may enhance healing in patients with UC by stimulating colonocyte proliferation and/or protein production. Mucosa from the descending colon was obtained from patients with UC (n = 5), Crohn's disease (n = 8), diverticulitis (n = 6), and cancer (normal tissue 10 cm from tumor; n = 10). Epithelial cells were isolated using dispase/collagenase and differential sedimentation and incubated for 4 hr at 37 degrees C with either Na butyrate (10 mM) or NaCl (10 mM). Protein synthesis was assessed by [14C]leucine incorporation and proliferation was determined with [3H]thymidine. Mean viability and purity were >88%. Spontaneous proliferation was significantly increased in UC when compared to diverticulitis and normal controls. Butyrate significantly increased protein synthesis in UC epithelial cells when compared to saline control. The therapeutic effects of butyrate in patients with UC may be due to its use by epithelial cells as a metabolic fuel to increase protein production and promote healing.

Improvement of structure and function in orthotopic small bowel transplantation in the rat by glutamine

Significant atrophy and impaired absorption occur in the heterotopically transplanted small intestinal isograft, and these deficits are corrected when the preferred fuel of the enterocyte, glutamine (Gln), is supplemented to total parenteral nutrition (TPN). In the orthotopic small bowel isograft, this study determined whether Gln-enriched TPN enhanced mucosal structure and function, and decreased bacterial translocation to mesenteric lymph nodes (MLN). Seventeen adult Lewis rats received orthotopic jejunal isografts and central venous catheters for TPN. Rats received either TPN with 2% Gln or the same TPN with isonitrogenous balanced nonessential amino acids for 10 days. Eight normal, chow-fed rats served as baseline controls. Mucosal villous height, surface area, crypt depth, weight, protein and DNA contents, brush border enzymes, 14C glucose absorption, and bacterial translocation to MLN were evaluated in both the graft and host jejunum and the control animals. Gln-enriched TPN significantly increased mucosal villous height (P < 0.01), surface area (P < 0.01), and glucose absorption (P < 0.01), and it reduced bacterial translocation (P < 0.05) when compared with the non-Gln TPN group. For most study variables, there were no significant differences between Gln-enriched TPN or baseline and between the graft and host jejunum for Gln- and non-Gln-supplemented animals. There were no significant differences in DNA content and brush border enzymes among groups. These results indicate that Gln-enriched TPN improves mucosal structure and glucose absorption and reduces bacterial translocation to MLN in the orthotopic small bowel isograft.