The concentration of apolipoprotein A-I decreases during experimentally induced acute-phase processes in pigs

Abstract

In this work, apolipoprotein A-I (ApoA-I) was purified from pig sera. The responses of this protein after sterile inflammation and in animals infected with Actinobacillus pleuropneumoniae or Streptococcus suis were investigated. Decreases in the concentrations of ApoA-I, two to five times lower than the initial values, were observed at 2 to 4 days. It is concluded that ApoA-I is a negative acute-phase protein in pigs.

FIG. 1.

(A) Protein patterns on SDS-12% polyacrylamide gels of the different fractions, obtained after the sequential ultracentrifugation of pig serum. Lane 1, VLDL and IDL; lane 2, LDL; lane 3, lighter HDL; lane 4, heavier HDL; lane 5, bottom fraction (1.250 g/ml < d); and lane 6, pig serum. (B) Amino acid sequence of the NH₂ terminal (top) of the purified 28-kDa protein compared to the pig ApoA-I sequence retrieved from the Swiss-Prot Database (the amino acid numbers differ because of the signal peptide). (C) Western blotting using specific antibodies against pig ApoA-I. Lane 1, pig serum; lane 2, purified lighter HDL.

FIG. 2.

Time courses of ApoA-I (A), pig MAP (B), haptoglobin (C), and CRP (D) concentrations in six pigs before and after turpentine oil injection. Abscissas, days after the injection (point zero was the injection day); ordinates, concentration of proteins in mg/ml. Each symbol represents a single animal. The horizontal line in the graph of CRP shows the detection limit (0.01 mg/ml).

FIG. 3.

Time course of ApoA-I and pig MAP concentrations before and subsequent days after bacterial infection with Actinobacillus pleuropneumoniae (A) and Streptococcus suis (B). Point zero was the infection day. Each symbol represents a single animal.