Widespread extrahepatic expression of acute-phase proteins in healthy chicken (Gallus gallus) tissues

Abstract

Acute phase proteins (APP) are plasma proteins that can modify their expression in response to inflammation caused by tissue injury, infections, immunological disorders or stress. Although APP are produced mainly in liver, extrahepatic production has also been described. As a prerequisite to get insight the expression of APP in chicken during diseases, this study investigated the presence of five APP, including alpha1-acid glycoprotein (AGP), Serum Amyloid A (SAA), PIT54, C-Reactive protein (CRP) and Ovotransferrin (OVT) in twenty tissues collected from healthy chicken (Gallus gallus) by quantitative Real Time PCR and immunohistochemistry. As expected, APP gene abundance was higher in liver compared with other tissues. The mRNA coding for CRP, OVT and SAA was detected in all analyzed tissues with a higher expression in gastrointestinal tract, respiratory and lymphatic samples. SAA expression was particularly high in cecal tonsil, lung, spleen and Meckel's diverticulum, whereas OVT in lung, bursa of Fabricius and pancreas. AGP and PIT54 mRNA expression were detected in all tissues but at negligible levels. Immunohistochemical expression of AGP and OVT was variably detected in different organs, being identified in endothelium of every tissue. Positive cells were present in the epithelium of the mucosal layer of gastrointestinal tract and kidney. Lung and central nervous system stained for both proteins. No positive staining was detected in lymphoid tissues and muscle. These results suggest that most tissues can express different amount of APP even in healthy conditions and are therefore capable to mount a local acute phase reaction.

Elevated faecal ovotransferrin concentrations are indicative for intestinal barrier failure in broiler chickens

“…The proteome analysis revealed low levels of ovotransferrin in faeces of non-challenged birds. This is in accordance with a recent study of Marques et al [ 30 ], showing low levels of ovotransferrin expression in epithelium and endothelium of the intestinal tract of healthy chickens. A wide range of infectious and non-infectious agents are known to damage the intestinal barrier in chickens, leading to gastrointestinal leakage and poor performance.…”

Temporal Effects of High Fishmeal Diet on Gut Microbiota and Immune Response in Clostridium perfringens-Challenged Chickens

“…Relative APP expression was higher in the liver compared with ileum, consistent with the previous report that the expression of APP genes was higher in liver than other tissue ( Marques et al, 2017 ). AGP is a highly glycosylated protein secreted by hepatocytes ( Murata et al, 2004 ).…”

Evaluation of Plasmatic Levels of Negative and Positive Acute Hepatic Phase Proteins in Patients who Underwent Major Surgery

“…If we consider the same amino acid substrate needed for protein synthesis [35], we can explain the same trend change in case of negative acute phase proteins and the differences found in case of positive acute phase proteins (graph 2 shows the slight increase after 24 hours in case of fibrinogen compared to CRP) [41]. Fibrinogen, being one of the largest acute phase proteins, requires for its synthesis a higher number of amino acids [42].…”

“…The fragments obtained were analyzed and the results showed the abundance of tyrosine, lysine and particularly glutamic acid, in case of both proteins [46,47]. CRP has a molecular mass of 115 kda and 1200 amino acids in its structure while fibrinogen (being one of the largest hepatic protein) has a mass of 340 kda and 2400 amino acids in its structure [33][34][35][36][37].…”