Changes in circulating lymphocyte subpopulations and mitogen-stimulated response in a rat infusion model of intra-abdominal infection

Fish oil-supplemented parenteral nutrition prolongs survival while beneficially altering phospholipids' Fatty Acid composition and modulating immune function in rat sepsis

We investigated the therapeutic effects of parenteral fish oil (FO) on survival and fatty acid profile in plasma and erythrocyte membranes, T-lymphocyte subsets, and plasma cytokines in a rat model of sepsis. Adult male Sprague-Dawley rats were subjected to cecal ligation and puncture-induced sepsis. For recovery, central venous catheterization was performed 2 days before sepsis was induced. Rats were randomly assigned to receive normal saline (n = 20) or total parenteral nutrition (PN) containing a standard soybean oil emulsion (n = 20) or FO-supplemented TPN (n = 20) at the onset of sepsis for 5 days. In the control group, rats were challenged by sham operation and underwent appropriate control treatment (n = 10). Sepsis led to a high mortality and body weight loss compared with sham operation. Total PN supplemented with FO, but not without FO, improved the survival compared with normal saline. Furthermore, parenteral infusion of FO increased the concentrations of eicosapentaenoic acid and docosahexaenoic acid, as well as the ratio of (eicosapentaenoic acid + docosahexaenoic acid) to arachidonic acid both in plasma and erythrocyte membrane. In addition, FO-supplemented TPN improved the percentages of CD3 and CD3CD4 T cells, as well as the CD4/CD8 ratio in spleen. Meanwhile, the percentage of regulatory T cells (CD4CD25Foxp3) among CD4 T cells was reduced by FO-supplemented TPN. Fish oil-supplemented TPN attenuated the production of high-mobility group box 1 and IL-10 in plasma. Moreover, parenteral FO decreased the bacterial loads in peritoneal lavage, blood, lung, and spleen. The present study suggests that FO-supplemented TPN initiated at the onset of sepsis improves survival, beneficially alters the lipids profile in plasma and erythrocyte membrane, modulates immune function, and regulates inflammatory response in a rat model.

A Limulus anti-LPS factor-derived peptide modulates cytokine gene expression and promotes resolution of bacterial acute infection in mice

Sepsis in experimental animals and humans has been associated with perturbed immune response. A major event contributing to the decrease in immune functions in septic disorders seems to be the inadequate balance of cytokines mediating the interactions between the innate and adaptive immune systems. We previously observed that a cyclic peptide derived from the Limulus anti-LPS factor (LALF), which partially protect mice from endotoxic shock lethality, has the ability to modulate cytokine secretion in vitro. We herein examined the effects of the LALF(31-52) peptide in an experimental model of Gram-negative peritoneal sepsis and analyzed the cytokine gene expression in the spleen and liver of peptide-treated mice. The prophylactic administration of LALF(31-52) abrogated the systemic TNF-alpha response, reduced organ damage and increased the survival of infected mice. Histological examination of spleen and liver in peptide-treated mice showed prevention of tissue damage induced by the high dose of Pseudomonas aeruginosa. This treatment modulates the cytokine gene expression in these tissues, stimulating IL-2, IL-12 and IL-13 mRNA synthesis, while IL-4 and IL-10 mRNA expression was not modified. This cytokine profile induced by the LALF-derived peptide seems to be favorable for host resistance against Gram-negative bacteria acute infection. In addition, peptide treatment was effective after the initiation of the systemic inflammatory response, promoting a significant increase in mice survival. These results further demonstrate the immunomodulatory potential of LALF(31-52) and are relevant for the design of prophylactic and therapeutic strategies for acute bacteria infection and sepsis, especially for preventing or ameliorating host immunity defects in these disorders.