Low HDL-C levels are associated with atherosclerosis and non-alcoholic steatohepatitis, and increased levels may reduce the risk of these diseases. Inhibition of cholesteryl ester transfer protein (CETP) activity is considered a promising strategy for increasing HDL-C levels. Since CETP is a self-antigen with low immunogenicity, we developed a novel CETP vaccine (Fc-CETP6) to overcome the low immunogenicity of CETP and for long-term inhibition of CETP activity. The vaccine consists of a rabbit IgG Fc domain for antigen delivery to antigen-presenting cells fused to a linear array of 6 repeats of a CETP epitope to efficiently activate B cells. Rabbits were fed a high fat/cholesterol (HFC) diet to induce atherosclerosis and NASH, and immunized with Fc-CETP6 vaccine. The Fc-CETP6 vaccine successfully elicited anti-CETP antibodies and lowered plasma CETP activity. The levels of plasma HDL-C and ApoA-I were higher, and plasma ox-LDL lower, in the Fc-CETP6-immunized rabbits as compared to the unimmunized HFC diet-fed rabbits. Pathological analyses revealed less lipid accumulation and inflammation in the aorta and liver of the Fc-CETP6-immunized rabbits. These results show that the Fc-CETP6 vaccine efficiently elicited antibodies against CETP and reduced susceptibility to both atherosclerosis and steatohepatitis induced by the HFC diet. Our findings suggest that the Fc-CETP6 vaccine may improve atherosclerosis and NASH and has high potential for clinical use.

With a total of 28 normal, healthy male adults, N balance studies with both Chinese mixed diet and egg diet were conducted at four protein levels with the former (0.45, 0.55, 0.65 and 0.75 g . kg-1 . day-1) and at three protein levels with the latter (0.35, 0.45 and 0.55 g . kg-1 . day-1) at ordinary levels of energy intake. By regression analysis, the mean maintenance N requirement (PRm) of the mixed Chinese diet calculated was 127.0 mg . kg-1 . day-1 (0.79 g protein . kg-1 . day-1). Estimate a allowance for individual variation to cover the 97.5% population (PR0.975) was 188.1 mg . kg-1 . day-1 (1.18 g protein . kg-1 . day-1). As for the egg diet series, PRm and PR0.975 were 98.2 mg N . kg-1 . day-1 (0.61 g protein . kg-1 . day-1) and 141.6 mg N . kg-1 . day-1 (0.89 g protein . kg-1 . day-1), respectively. Net protein utilization (NPU) of egg diet protein was significantly higher than that of the Chinese mixed diet protein (P less than 0.01), with mean values of 56 versus 43. True digestibility of the mixed diet and egg diet proteins was 96.5 and 98%, respectively. The efficiency of utilization of the Chinese mixed diet protein was 73-77% of the egg protein, based on relative N requirements.

Comparison between the positive N balance data and the actual N deposition in the same adult animals was made. In experiment 1, 24 mature 9-month old male rats were divided into three groups. One group was killed on day zero and served as the control. The two other groups were fed 25 or 49% casein diet for 8 weeks. Body weight was kept relatively constant by regulating the dietary intake. The N balance study (including body hair N loss) was conducted thrice intermittently, and body N was determined at the end of the experiment. It was found that the mean total-body N of the 49% casein groups was 967 mg higher than the 25% casein groups and 885 mg higher than the day-zero control group (P less than 0.01). The calculated N retention during the experimental period was 1876 mg for the 49% casein group. In experiment 2, a similar study was conducted except that the 25 and 49% casein diets were fed ad libitum, and body weight gain was allowed. The total-body N values of both test groups at the end of the feeding period were very close to each other, but significantly higher than that of the day-zero control group (P less than 0.01).

A nontoxic Pseudomonas aeruginosa exotoxin A (PE), which has the carboxyl-terminal 38 amino acid residues of native PE deleted, was used as an antigen to immunize BALB/c mice, which were then challenged with native PE in order to raise monoclonal antibodies (MAbs) that can neutralize PE cytotoxicity. A murine MAb against PE, designated MAb B7, was established. MAb B7 was characterized in terms of its ability to neutralize PE cytotoxicity, epitope mapping, inhibition of PE receptor binding, and influence on cellular processing of PE and ADP-ribosylation activities. We found that MAb B7 could neutralize PE cytotoxicity in cell culture and in BALB/c mice. The epitope recognized by MAb B7 was mapped to the carboxyl-terminal amino acid residues 575 to 595 of PE. Consistent with the results of epitope mapping, MAb B7 did not block PE receptor-binding activity or the cellular processing of PE but strongly inhibited the ADP-ribosylating activity of PE. In addition, MAb B7 retained strong binding to PE even at pH 4.0, indicating that the complex of MAb B7 and PE is stable in the phagolysosome. On the basis of these observations, the neutralization of PE cytotoxicity by MAb B7 could be due to its binding to the carboxyl terminus of PE. As a result, MAb B7 may interfere with the interaction of the carboxyl-end amino acid residues REDLK of PE with cellular factors. However, we could not rule out the possibility that MAb B7 directly blocks the ADP-ribosylation activity of PE in the cytosol.