Development of monoclonal antibodies against human CYP11B1 and CYP11B2

1. The final enzymes in the biosynthesis of aldosterone and cortisol are by the cytochrome P450 CYP11B2 and CYP11B1, respectively. The enzymes are 93% homologous at the amino acid level and specific antibodies have been difficult to generate. 2. Mice and rats were immunized with multiple peptides conjugated to various immunogenic proteins and monoclonal antibodies were generated. The only peptide sequences that generated specific antibodies were amino acids 41-52 for the CYP11B2 and amino acids 80-90 for the CYP11B1 enzyme. 3. The mouse monoclonal CYP11B2-41 was specific and sensitive for use in western blots and produced specific staining of the zona glomerulosa of normal adrenal glands. The rat monoclonal CYP11B1-80 also detected a single band by western blot and detected only the zona fasciculata. Triple immunofluorescence of the adrenal demonstrated that the CYP11B1 and the CYP11B2 did not co-localize, while as expected the CYP11B1 co-localized with the 17α-hydroxylase.

Regulation of adrenal glucocorticoid synthesis by interleukin-10: a preponderance of IL-10 receptor in the adrenal zona fasciculata

Several lines of evidence indicate that cytokines can affect adrenal function. To date most of these cytokines have been shown to be pro-inflammatory, such as interleukin (IL)-1, tumor necrosis factor (TNFalpha), and IL-6. However, we have previously shown that IL-10-/- (IL-10 knockout) mice have higher serum corticosterone levels than IL-10+/+ (wild type) mice following acute immune and physiologic stress, implying that IL-10, an anti-inflammatory cytokine, regulates glucocorticoid synthesis in a negative manner. Here, we show that IL-10 knockout mice produce more corticosterone under basal conditions as well (shown by ELISA). We further support this contention by showing that in Y-1 adrenocortical cells IL-10 inhibits steroid production (StAR) (measured by the production of the corticosterone precursor, progesterone), the expression of steroidogenic acute regulatory protein (semi-quantitative RT-PCR), as well as the activity of the proximal steroidogenic enzymes P450scc and/or 3beta-hydroxysteroid dehydrogenase (3beta-HSD) (measured by progesterone production in 22(R)-hydroxycholesterol-treated cells). Interestingly, all of the above-mentioned effects of IL-10 occur through its inhibition of ACTH effects, but not by IL-10 alone. Furthermore, immunocytochemistry data shows that the region of the adrenal gland responsible for the vast majority of corticosterone synthesis, the zona fasciculata, predominantly expresses the IL-10 receptor 1 (IL-10R1), with little expression in the zona glomerulosa and reticularis. These data demonstrate that IL-10 could play an important role in the regulation of glucocorticoid biosynthesis and in maintenance of homeostasis and immunity during periods of stress.

New insights into zonal differentiation of adrenal autotransplants in the rat: an immunohistochemical study

Adrenal gland autotransplantation, an interesting model of adrenal regeneration, provides the reconstruction of distinct functional and morphological zonae. An immunohistochemical study of the adrenal gland of adult male rats after autotransplantation and endothelin-1 (ET-1) stimulation was carried out. The technique involved total adrenalectomy and immediate autotransplantation of small adrenal pieces under the skin of the dorsal region. The animals were killed 90 days after the autotransplantation and 1 h after intravenous ET-1 administration. Sections of recovered adrenal grafts were incubated with IZAb, a monoclonal antibody which interacts with an antigen (IZAg) predominantly found in rat adrenal inner zones. Saline-treated control autotransplanted animals showed IZAb immunostaining in almost all adrenocortical tissue, with the exception of small clusters of cells beneath the capsule. ET-1-treated animals exhibited an extended zone devoid of immunostaining and located in the subcapsular area. In addition, ET-1-stimulated animals showed significant increases in aldosterone as well as corticosterone concentrations in plasma. These results revealed that ET-1 stimulated the development of an extended subcapsular zone lacking IZAg expression, an effect that suggests its role in zona glomerulosa induction in these animals.

The development of the adrenal cortex in the rat. An immunohistochemical study

The Inner Zone Antibody (IZAb) is a monoclonal antibody which interacts with an antigen found predominantly in rat adrenal inner cortical zones. Since its expression increases after ACTH treatment the antigen may have a role in steroidogenesis although, so far, this has not yet been fully characterised. Due to its molecular weight, it cannot be any of the known cytochrome P450 proteins. In this study we examined the expression of IZAb in male and female rats throughout their postnatal development and in aged animals. In a different set of animals, blood was collected for hormonal assays and the adrenals stained with classical methods. The staining with IZAb was clear from the first post-natal day. The zona glomerulosa which was always present at birth, was easily distinguished and unstained. The staining in the inner zone cells was fainter at birth and increased progressively until postnatal day 20. Afterwards these cells were remarkably stained at all ages. Medullary cells were also present from birth although they were generally found in clusters instead of constituting a well defined zone. Cortical cells appeared in the medullary zone at all ages after its complete development. The zona glomerulosa increased in size until approximately postnatal day 40 while the inner zones increased until day 70. The area of the cortex was significantly different between the two sexes from day 50 onwards and this was predominantly due to differences in the zona fasciculata. Corticosterone levels increased until approximately day 25 in the male rat and until day 45 in the female.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of the adrenocortical inner zone antigen

Previous studies using a mouse monoclonal antibody (IZAb) have identified inner zone-specific antigens (IZAg 1 and 2) in the rat adrenal cortex. The expression of IZAg1 is enhanced by dibutyryl-cyclic AMP or ACTH in vitro and by in vivo ACTH treatment. These studies also suggest that IZAg may be involved in steriogenesis in rat adrenals. Using sensitive detection methods, the distribution of IZAg in adrenals from other species and in other rat tissues was studied. Pig and rabbit adrenals expressed an IZAb-immunoreactive protein with molecular mass identical with that of IZAg1, but no immunoreactivity was detected in bovine, guinea-pig or mouse adrenals. In the rabbit adrenal, as in the rat, IZAb bound only to zonae fasciculata/reticularis cells. However, the whole adrenal cortex in the pig immunoreacted with IZAb. Although immunofluorescence was observed in human adrenal sections, predominantly in the zona reticularis, no significant immunoreactive protein band was detected by immunoblot analysis. Apart from the zonae fasciculata/reticularis in the adrenal gland, an IZAb-immunoreactive protein with a molecular mass of 26,000 Da, corresponding to IZAg1, was also found in rat hepatocytes, renal tubules, ovary (corpus luteum, interstitial cells, theca interna of mature follicles) and Leydig cells. The observations suggest that IZAg may be involved in the processes of biosynthesis, metabolism and/or excretion of steroid hormones.