Proinflammatory cytokine interleukin-1ß suppresses cold-induced thermogenesis in adipocytes.

In this study, we investigated the effects of interleukin-1ß (IL-1ß), a typical proinflammatory cytokine on the ß-adrenoreceptor-stimulated induction of uncoupling protein 1 (UCP1) expression in adipocytes. IL-1ß mRNA expression levels were upregulated in white adipose tissues of obese mice and in RAW264.7 macrophages under conditions designed to mimic obese adipose tissue. Isoproterenol-stimulated induction of UCP1 mRNA expression was significantly inhibited in C3H10T1/2 adipocytes by conditioned medium from lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages in comparison with control conditioned medium. This inhibition was significantly attenuated in the presence of recombinant IL-1 receptor antagonist and IL-1ß antibody, suggesting that activated macrophage-derived IL-1ß is an important cytokine for inhibition of ß-adrenoreceptor-stimulated UCP1 induction in adipocytes. IL-1ß suppressed isoproterenol-induced UCP1 mRNA expression in C3H10T1/2 adipocytes, and this effect was partially but significantly abrogated by inhibition of extracellular signal-regulated kinase (ERK). IL-1ß also suppressed the isoproterenol-induced activation of the UCP1 promoter and transcription factors binding to the cAMP response element. Moreover, intraperitoneal administration of IL-1ß suppressed cold-induced UCP1 expression in adipose tissues. These findings suggest that IL-1ß upregulated in obese adipose tissues suppresses ß-adrenoreceptor-stimulated induction of UCP1 expression through ERK activation in adipocytes.

Inflammation induced by RAW macrophages suppresses UCP1 mRNA induction via ERK activation in 10T1/2 adipocytes.

Recently, it has been demonstrated that uncoupling protein-1 (UCP1)-expressing white adipocytes (brown-like adipocytes) are important for energy expenditure in white adipose tissue (WAT), in which energy expenditure decreases under obese conditions. However, the relationship between the induction of brown-like adipocytes and the decrease in energy expenditure in obese WAT remains to be elucidated. Here, we show that proinflammatory cytokines derived from activated macrophages suppress the induction of UCP1 promoter activity and mRNA expression via an extracellular signal-related kinase (ERK) in white adipocytes. The coculture with RAW264.7 (RAW) macrophages suppressed the induction of UCP1 mRNA expression by isoproterenol (ISO), a typical ß-adrenergic receptor agonist, in C3H10T1/2 (10T1/2) adipocytes. A conditioned medium derived from lipopolysaccharide (LPS)-activated macrophages and tumor necrosis factor-α (TNF-α) also suppressed the induction of UCP1 mRNA but did not affect its mRNA stability. By using a luciferase reporter assay system, the conditioned medium and TNF-α also suppressed the activity of the UCP1 promoter and transcriptional factors binding to the cAMP response element (CRE). Importantly, PD98059, an ERK inhibitor, partially abrogated the suppression of UCP1 promoter activation and mRNA induction. These results indicate that ERK is an important factor in the suppression of UCP1 transcriptional activation in the interaction between white adipocytes and activated macrophages. This report suggests a possible mechanism of the UCP1 transcriptional suppression in white adipocytes associated with obese and diabetic conditions.

Stimulating macrophage activity in mice and humans by oral administration of quillaja saponin.

Quillaja saponin (QS) was examined for its immunostimulating effect on mice and humans after oral administration. Mice fed QS for 24 h significantly increased in chemotactic and phagocytosis activities of peritoneal macrophages. This enhancing effect in both activities continued for 4-d after QS administration. Mice fed QS for 24 h prior to an interperitoneal challenge with Escherichia coli showed a higher survival rate than the control group. Peripheral blood analysis of volunteers showed significant increases in chemotactic and phagocytosis activities after oral administration of QS for 7 d. Furthermore, the volunteers did not show significant changes in immunoglobulin, transaminase, IL-1α, or TNF-α levels, or in serum albumin concentrations. Thus orally administered QS can effectively enhance the immune response through stimulation of macrophages without adverse effects.

Multiple biological functions of novel basic proteins isolated from duck egg white: duck basic protein small 1 (dBPS1) and 2 (dBPS2).

Biological functions of duck basic protein small 1 (dBPS(1)) and 2 (dBPS(2)) were investigated by in vitro experiments. Results of agarose gel retardation assay indicated that dBPS(1) and dBPS(2) associate with RNA. Addition of NaCl or urea induced partial dissociation of dBPS(1)/dBPS(2)-RNA complex, implying that electrostatic interaction, hydrophobic interaction, and hydrogen bonds are involved in the association of dBPS(1)/dBPS(2) to RNA. dBPS(1) and dBPS(2) inhibited pancreatic lipase activity with the fifty percent inhibitory concentration (IC(50)) of 250 and 100 µg/mL, respectively. Peptic hydrolysates of dBPS(1) and those of dBPS(2) showed a potent angiotensin I-converting enzyme (ACE) inhibition with an IC(50) of 22.5 and 49.6 mg/L. The most potent ACE-inhibitory peptide was a nanopeptide (EKKGFCAGY) from dBPS(1) and an octapeptide (KYCPKVGY) from dBPS(2). These multiple biological functions of dBPS(1) and dBPS(2) may contribute to reducing the risk of lifestyle diseases.

Structural and physicochemical characteristics of novel basic proteins isolated from duck egg white.

Novel basic proteins, duck basic protein small 1 (dBPS(1)) and 2 (dBPS(2)), were isolated from duck egg white by cation-exchange and gel filtration chromatography. Protein sequence analyses indicated that they possessed 39 amino acid residues with three disulfide bonds. The amino acid sequence of dBPS(1) showed 45% identity with dBPS(2). The amino acid sequence of dBPS(2) was the same as cygnin, a small protein from black swan, and strongly homologous with meleagrin from turkey and chicken. Phylogenic relationships implied that dBPS(1) and dBPS(2) share a common ancestry with cygnin and meleagrin. Based on MALDI-TOF mass spectra, the molecular masses of dBPS(1) and dBPS(2) were 4,373, and the 4,486 Da. pI of dBPS(1) and dBPS(2) elucidated by isoelectric focusing were 9.35 and 9.44. FT-IR spectra classified these proteins as (beta) proteins. Both dBPS(1) and dBPS(2), possessed high heat stability, Td 101.2 and 98.3 degrees C. Indirect ELISA results showed that the dBPS(1)/dBPS(2)-related proteins were distributed in the oviduct and gallbladder.