Impact of animal strain on gene expression in a rat model of acute cardiac rejection

Circulating cytokine portraits can differentiate between allograft rejection and pulmonary infection in cardiac transplant rats

OBJECTIVES

Cardiac rejection and infection are the leading causes of morbidity and mortality after transplant representing with similar non-specific symptoms. Early discrimination is crucial yet challenging. We proposed that aberrant serum cytokine portraits exist in pulmonary infection and allograft rejection, and such profiles might aid in timely differential diagnosis.

METHODS

Lewis rat received Wistar rat heart allografts. Allograft rejection (n = 5) and pulmonary infection (n = 7) were induced via cessation of cyclosporine injection and intratracheal inoculation of Pseudomonas aeruginosa, respectively, and pathologically confirmed. A non-rejection and non-infection group (n = 5) was served as healthy controls. The circulating cytokine profiles of the study objects were then simultaneously measured using a multiplex quantitative cytokine array.

RESULTS

Thirteen cytokines [B7-2, β-nerve growth factor (NGF), chemokine (C-X3-C motif) ligand 1 (Fractalkine), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-γ), interleukin beta (IL-β), IL-2, IL-4, IL-10, chemokine (C-X-C motif) ligand 5 (LIX), L-selectin, chemokine (C-C motif) ligand 2 (MCP-1), brain creatine kinase (TCK-1) and tumour necrosis factor alpha (TNF-α)] were up-regulated in allograft rejecting animals. Among them, B7-2, β-NGF, Fractalkine, GM-CSF, IFN-γ, IL-β, IL-2, IL-4, LIX, MCP-1 and TCK-1 were significantly increased compared with infection rats (all P-values <0.05). B7-2, CNIC-1 and CNIC-2 were increased in infection animals when compared with healthy controls (900.85 ± 259.30 vs 175.04 ± 161.07 pg/ml, 319.68 ± 264.91 vs 13.50 ± 0.00 pg/ml and 51.424 ± 29.51 vs 5.24 ± 1.30 pg/ml, respectively, all P-values <0.05).

CONCLUSIONS

The present study demonstrated fluctuations in circulating cytokine portraits in cardiac allograft rejection and bacterial pulmonary infection after transplant. Such disease-specific cytokine patterns might facilitate early discrimination between rejection and infection.

Whole Blood Transcriptomics Is Relevant to Identify Molecular Changes in Response to Genetic Selection for Feed Efficiency and Nutritional Status in the Pig

The molecular mechanisms underlying feed efficiency need to be better understood to improve animal efficiency, a research priority to support a competitive and sustainable livestock production. This study was undertaken to determine whether pig blood transcriptome was affected by differences in feed efficiency and by ingested nutrients. Growing pigs from two lines divergently selected for residual feed intake (RFI) and fed isoproteic and isocaloric diets contrasted in energy source and nutrients were considered. Between 74 and 132 days of age, pigs (n = 12 by diet and by line) received a regular diet rich in cereals and low in fat (LF) or a diet where cereals where partially substituted by lipids and fibers (HF). At the end of the feeding trial, the total number of white blood cells was not affected by the line or by the diet, whereas the red blood cell number was higher (P<0.001) in low RFI than in high RFI pigs. Analysis of the whole blood transcriptome using a porcine microarray reveals a higher number of probes differentially expressed (DE) between RFI lines than between diets (2,154 versus 92 probes DE, P<0.01). This corresponds to 528 overexpressed genes and 477 underexpressed genes in low RFI pigs compared with high RFI pigs, respectively. Overexpressed genes were predominantly associated with translational elongation. Underexpressed genes were mainly involved in the immune response, regulation of inflammatory response, anti-apoptosis process, and cell organization. These findings suggest that selection for RFI has affected the immune status and defense mechanisms of pigs. Genes DE between diets were mainly related to the immune system and lipid metabolism. Altogether, this study demonstrates the usefulness of the blood transcriptome to identify the main biological processes affected by genetic selection and feeding strategies.

Host-based Th2 cell therapy for prolongation of cardiac allograft viability

Donor T cell transfusion, which is a long-standing approach to prevent allograft rejection, operates indirectly by alteration of host T cell immunity. We therefore hypothesized that adoptive transfer of immune regulatory host Th2 cells would represent a novel intervention to enhance cardiac allograft survival. Using a well-described rat cardiac transplant model, we first developed a method for ex vivo manufacture of rat host-type Th2 cells in rapamycin, with subsequent injection of such Th2.R cells prior to class I and class II disparate cardiac allografting. Second, we determined whether Th2.R cell transfer polarized host immunity towards a Th2 phenotype. And third, we evaluated whether Th2.R cell therapy prolonged allograft viability when used alone or in combination with a short-course of cyclosporine (CSA) therapy. We found that host-type Th2.R cell therapy prior to cardiac allografting: (1) reduced the frequency of activated T cells in secondary lymphoid organs; (2) shifted post-transplant cytokines towards a Th2 phenotype; and (3) prolonged allograft viability when used in combination with short-course CSA therapy. These results provide further support for the rationale to use “direct” host T cell therapy for prolongation of allograft viability as an alternative to “indirect” therapy mediated by donor T cell infusion.